diff --git a/Graduator/Graduator.xcodeproj/project.pbxproj b/Graduator/Graduator.xcodeproj/project.pbxproj
index 8c3656d..2041f39 100644
--- a/Graduator/Graduator.xcodeproj/project.pbxproj
+++ b/Graduator/Graduator.xcodeproj/project.pbxproj
@@ -20,6 +20,8 @@
 		EC242B8A2A1FCECA006FE760 /* AverageBlockView.swift in Sources */ = {isa = PBXBuildFile; fileRef = EC242B892A1FCECA006FE760 /* AverageBlockView.swift */; };
 		EC5FE5A52A20882F0028AA5F /* Formatters.swift in Sources */ = {isa = PBXBuildFile; fileRef = EC5FE5A42A20882F0028AA5F /* Formatters.swift */; };
 		EC8BAD162A3465230062226B /* UnitsStore.swift in Sources */ = {isa = PBXBuildFile; fileRef = EC8BAD152A3465230062226B /* UnitsStore.swift */; };
+		EC8BAD1A2A34BC170062226B /* WeightedGrade.swift in Sources */ = {isa = PBXBuildFile; fileRef = EC8BAD192A34BC170062226B /* WeightedGrade.swift */; };
+		EC8BAD1C2A34BE4C0062226B /* WeightedAverageCalculator.swift in Sources */ = {isa = PBXBuildFile; fileRef = EC8BAD1B2A34BE4C0062226B /* WeightedAverageCalculator.swift */; };
 		ECB2FFCE2A23C4A700FF9F91 /* SubjectFormView.swift in Sources */ = {isa = PBXBuildFile; fileRef = ECB2FFCD2A23C4A700FF9F91 /* SubjectFormView.swift */; };
 		ECB2FFD02A23C4B700FF9F91 /* SubjectFormVM.swift in Sources */ = {isa = PBXBuildFile; fileRef = ECB2FFCF2A23C4B700FF9F91 /* SubjectFormVM.swift */; };
 		ECC581D22A1D085B006C55EF /* GraduatorApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = ECC581D12A1D085B006C55EF /* GraduatorApp.swift */; };
@@ -43,6 +45,8 @@
 		EC242B892A1FCECA006FE760 /* AverageBlockView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AverageBlockView.swift; sourceTree = "<group>"; };
 		EC5FE5A42A20882F0028AA5F /* Formatters.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Formatters.swift; sourceTree = "<group>"; };
 		EC8BAD152A3465230062226B /* UnitsStore.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UnitsStore.swift; sourceTree = "<group>"; };
+		EC8BAD192A34BC170062226B /* WeightedGrade.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WeightedGrade.swift; sourceTree = "<group>"; };
+		EC8BAD1B2A34BE4C0062226B /* WeightedAverageCalculator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WeightedAverageCalculator.swift; sourceTree = "<group>"; };
 		ECB2FFCD2A23C4A700FF9F91 /* SubjectFormView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SubjectFormView.swift; sourceTree = "<group>"; };
 		ECB2FFCF2A23C4B700FF9F91 /* SubjectFormVM.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SubjectFormVM.swift; sourceTree = "<group>"; };
 		ECC581CE2A1D085B006C55EF /* Graduator.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Graduator.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -183,6 +187,8 @@
 				EC242B6B2A1F81AE006FE760 /* Subject.swift */,
 				EC242B692A1F8189006FE760 /* Unit.swift */,
 				EC242B6D2A1F81CC006FE760 /* UnitsManager.swift */,
+				EC8BAD192A34BC170062226B /* WeightedGrade.swift */,
+				EC8BAD1B2A34BE4C0062226B /* WeightedAverageCalculator.swift */,
 			);
 			path = Model;
 			sourceTree = "<group>";
@@ -265,6 +271,8 @@
 				EC8BAD162A3465230062226B /* UnitsStore.swift in Sources */,
 				EC242B7F2A1F83BF006FE760 /* UnitsManagerVM.swift in Sources */,
 				EC242B7B2A1F838C006FE760 /* UnitViewCell.swift in Sources */,
+				EC8BAD1C2A34BE4C0062226B /* WeightedAverageCalculator.swift in Sources */,
+				EC8BAD1A2A34BC170062226B /* WeightedGrade.swift in Sources */,
 				EC242B6C2A1F81AE006FE760 /* Subject.swift in Sources */,
 				EC242B8A2A1FCECA006FE760 /* AverageBlockView.swift in Sources */,
 				ECB2FFD02A23C4B700FF9F91 /* SubjectFormVM.swift in Sources */,
diff --git a/Graduator/Graduator/Model/Subject.swift b/Graduator/Graduator/Model/Subject.swift
index e80cdae..49d21eb 100644
--- a/Graduator/Graduator/Model/Subject.swift
+++ b/Graduator/Graduator/Model/Subject.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-struct Subject : Identifiable, Codable {
+struct Subject : Identifiable, Codable, WeightedGrade {
     let id: UUID
     var name: String
     var weight: Int
diff --git a/Graduator/Graduator/Model/Unit.swift b/Graduator/Graduator/Model/Unit.swift
index 1a1b3d3..445bf2c 100644
--- a/Graduator/Graduator/Model/Unit.swift
+++ b/Graduator/Graduator/Model/Unit.swift
@@ -7,28 +7,16 @@
 
 import Foundation
 
-struct Unit : Identifiable, Codable {
+struct Unit : Identifiable, Codable, WeightedGrade {
     let id: UUID
     var name: String
     var weight: Int
+    var grade: Double? { getAverage() }
     var isProfessional: Bool
     var code: Int
     var subjects: [Subject]
     
-    // FIXME DRY
     func getAverage() -> Double? {
-        var totalWeight = 0
-        var weightedSum = 0.0
-
-        for subject in subjects {
-            if let grade = subject.grade {
-                totalWeight += subject.weight
-                weightedSum += grade * Double(subject.weight)
-            }
-        }
-
-        guard totalWeight > 0 else { return nil }
-
-        return weightedSum / Double(totalWeight)
+        return WeightedAverageCalculator.average(elements: subjects)
     }
 }
diff --git a/Graduator/Graduator/Model/UnitsManager.swift b/Graduator/Graduator/Model/UnitsManager.swift
index fac8c28..fe2876f 100644
--- a/Graduator/Graduator/Model/UnitsManager.swift
+++ b/Graduator/Graduator/Model/UnitsManager.swift
@@ -36,27 +36,11 @@ struct UnitsManager {
     }
     
     func getTotalAverage() -> Double? {
-        return getAverage(units: units)
+        return WeightedAverageCalculator.average(elements: units)
     }
     
     func getProfessionalAverage() -> Double? {
-        return getAverage(units: units.filter { $0.isProfessional })
-    }
-    
-    // FIXME DRY
-    func getAverage(units: [Unit]) -> Double? {
-        var totalWeight = 0
-        var weightedSum = 0.0
-
-        for unit in units {
-            if let grade = unit.getAverage() {
-                totalWeight += unit.weight
-                weightedSum += grade * Double(unit.weight)
-            }
-        }
-        
-        guard totalWeight > 0 else { return nil }
-        
-        return weightedSum / Double(totalWeight)
+        let professionalUnits = units.filter { $0.isProfessional }
+        return WeightedAverageCalculator.average(elements: professionalUnits)
     }
 }
diff --git a/Graduator/Graduator/Model/WeightedAverageCalculator.swift b/Graduator/Graduator/Model/WeightedAverageCalculator.swift
new file mode 100644
index 0000000..7ec2a1f
--- /dev/null
+++ b/Graduator/Graduator/Model/WeightedAverageCalculator.swift
@@ -0,0 +1,26 @@
+//
+//  WeightedAverageCalculator.swift
+//  Graduator
+//
+//  Created by etudiant on 2023-06-10.
+//
+
+import Foundation
+
+struct WeightedAverageCalculator {
+    static func average<T: WeightedGrade>(elements: [T]) -> Double? {
+        var totalWeight = 0
+        var weightedSum = 0.0
+
+        for element in elements {
+            if let grade = element.grade {
+                totalWeight += element.weight
+                weightedSum += grade * Double(element.weight)
+            }
+        }
+
+        guard totalWeight > 0 else { return nil }
+
+        return weightedSum / Double(totalWeight)
+    }
+}
diff --git a/Graduator/Graduator/Model/WeightedGrade.swift b/Graduator/Graduator/Model/WeightedGrade.swift
new file mode 100644
index 0000000..8d805c3
--- /dev/null
+++ b/Graduator/Graduator/Model/WeightedGrade.swift
@@ -0,0 +1,13 @@
+//
+//  WeightedGrade.swift
+//  Graduator
+//
+//  Created by etudiant on 2023-06-10.
+//
+
+import Foundation
+
+protocol WeightedGrade {
+    var weight: Int { get }
+    var grade: Double? { get }
+}