老师代码有哪里需要优化的吗？

来源：4-5 编程练习

原来是晓琪_

2019-08-27 14:26:37

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>三种定义方式</title>
</head>
<body>
    <script type="text/javascript">
    // 在此处补充代码
    var add = function (num1, num2) {
    document.write('结果为: ' + (num1 + num2));
    }
    var subtract = function (num1, num2) {
    return num1 - num2;
    }
    var multiply = function (num1, num2) {
    return num1 * num2;
    }
    add(subtract(21, 32), multiply(24, 5));
    </script>
</body>
</html>