function add(a, b) {
    return a + b;
}

function substract(a, b) {
    return a - b;
}

function multiply(a, b) {
    return a * b;
}

function divide(a, b) {
    return a / b;
}

function operate(equals) {
    switch(equals.operator) {
        case "+":
            return add(equals.a, equals.b);
        case "-":
            return substract(equals.a, equals.b);
        case "*":
            return multiply(equals.a, equals.b);
        case "/":
            return divide(equals.a, equals.b);
    }
}

let operation = {
    a: 0,
    operator: "+",
    b: 0,
}