Zesty Interview Question

class Foo { add5(value){ value = value + 5; return value; } addElement(arr, elem) { arr.push(elem); return arr; } increment(arr) { arr[0]++; return arr; } } let fooInstance = new Foo(); let a = 9; const arr1 = [1,2]; const arr2 = [1,2,1]; fooInstance.add5(a); fooInstance.addElement(arr1, 3); fooInstance.increment(arr2); console.log(a); // ??? console.log(arr1); // ?? console.log(arr2); // ??