diff --git a/src/main/java/fr/nancy/iut/CalcEngine.java b/src/main/java/fr/nancy/iut/CalcEngine.java
index 14bc40d97f4b0cccda0346dbf1f976bd825c6209..766fb7c896c985e6a79de9e533c025718d466564 100755
--- a/src/main/java/fr/nancy/iut/CalcEngine.java
+++ b/src/main/java/fr/nancy/iut/CalcEngine.java
@@ -69,11 +69,11 @@ public class CalcEngine
      */
     public void equals()
     {
-        if (previousOperator == '+') {
-            displayValue = leftOperand + displayValue;
+        if (previousOperator == '-') {
+            displayValue = leftOperand - displayValue;
         }
         else {
-            displayValue = leftOperand - displayValue;
+            displayValue = leftOperand + displayValue;
         }
         leftOperand = 0;
     }
diff --git a/src/test/java/fr/nancy/iut/CalcEngineTest.java b/src/test/java/fr/nancy/iut/CalcEngineTest.java
index aa92ec89b14afb81eee5a4d5b051fcec522d531d..72ed24d85387fda0067d48e25f3e52e05a7777b8 100644
--- a/src/test/java/fr/nancy/iut/CalcEngineTest.java
+++ b/src/test/java/fr/nancy/iut/CalcEngineTest.java
@@ -6,14 +6,9 @@ import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class CalcEngineTest {
-    private CalcEngine engine;
-
-    @BeforeEach
-    void setUp() {
-        engine = new CalcEngine();
-    }
     @Test
     void testClear() {
+        CalcEngine engine = new CalcEngine();
         engine.numberPressed(1);
         engine.numberPressed(2);
         engine.numberPressed(3);
@@ -24,6 +19,7 @@ public class CalcEngineTest {
 
     @Test
     void testEquals() {
+        CalcEngine engine = new CalcEngine();
         engine.numberPressed(1);
         engine.numberPressed(2);
         engine.numberPressed(3);
@@ -34,26 +30,31 @@ public class CalcEngineTest {
 
     @Test
     void testGetAuthor() {
+        CalcEngine engine = new CalcEngine();
         assertEquals("Hacker T. Largebrain", engine.getAuthor());
     }
 
     @Test
     void testGetDisplayValue() {
+        CalcEngine engine = new CalcEngine();
         assertEquals(0, engine.getDisplayValue());
     }
 
     @Test
     void testGetTitle() {
+        CalcEngine engine = new CalcEngine();
         assertEquals("Super Calculator", engine.getTitle());
     }
 
     @Test
     void testGetVersion() {
+        CalcEngine engine = new CalcEngine();
         assertEquals("version 0.2", engine.getVersion());
     }
 
     @Test
     void testMinus() {
+        CalcEngine engine = new CalcEngine();
         engine.numberPressed(1);
         engine.numberPressed(2);
         engine.numberPressed(3);
@@ -70,6 +71,7 @@ public class CalcEngineTest {
 
     @Test
     void testNumberPressed() {
+        CalcEngine engine = new CalcEngine();
         assertEquals(0, engine.getDisplayValue());
         engine.numberPressed(1);
         assertEquals(1, engine.getDisplayValue());
@@ -81,6 +83,7 @@ public class CalcEngineTest {
 
     @Test
     void testPlus() {
+        CalcEngine engine = new CalcEngine();
         engine.numberPressed(1);
         engine.numberPressed(2);
         engine.numberPressed(3);