fix sum

Author: andre15silva

.github/workflows/tests.yml

@@ -9,7 +9,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v3
         with:
-          node-version: '16'
+          node-version: '22.13.1'
 
       - name: Install dependencies
         run: npm ci

src/main/js/appMath.js

@@ -1,6 +1,6 @@
 class AppMath {
     sum(a, b) {
-        return a - b;
+        return a + b;
     }
 
     subtract(a, b) {