Shorthand operations in JavaScript

For such operations, when to the variable its current value plus something else is written, there is a special shortened syntax. This syntax uses the special operator += instead of the normal assignment. Let's look at an example:

let num = 1;
num += 3; // equivalent to num = num + 3;

There are similar operators for other mathematical operations:

let num = 2;
num -= 3; // equivalent to num = num - 3;

let num = 2;
num *= 3; // equivalent to num = num * 3;

let num = 2;
num /= 3; // equivalent to num = num / 3;

Modify this code to use the above described shorthand operations:

let num = 47;
num = num + 7;
num = num - 18;
num = num * 10;
num = num / 15;
alert(num);