Updated method for calculating balance

src/main/java/no/ntnu/idatt1002/demo/data/Economics/Overview.java

@@ -77,12 +77,12 @@ public class Overview {
     }
 
     /**
-     * Method for updating the total revenue
-     * by taking the total sum of the income register
+     * Method for updating the total balance
+     * by taking the max amount of the budget
      * minus the total sum of the expense register.
      */
     public void updateBalance(){
-        balance = incomeRegister.getTotalSum() - expenseRegister.getTotalSum();
+        balance = budget.getMaxAmount() - expenseRegister.getTotalSum();
     }
 
     /**