freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md

---
id: 56533eb9ac21ba0edf2244b0
title: Compound Assignment With Augmented Subtraction
challengeType: 1
videoUrl: 'https://scrimba.com/c/c2Qv7AV'
forumTopicId: 16660
dashedName: compound-assignment-with-augmented-subtraction
---

# --description--

Like the `+=` operator, `-=` subtracts a number from a variable.

`myVar = myVar - 5;`

will subtract `5` from `myVar`. This can be rewritten as:

`myVar -= 5;`

# --instructions--

Convert the assignments for `a`, `b`, and `c` to use the `-=` operator.

# --hints--

`a` should equal `5`.

```js
assert(a === 5);
```

`b` should equal `-6`.

```js
assert(b === -6);
```

`c` should equal `2`.

```js
assert(c === 2);
```

You should use the `-=` operator for each variable.

```js
assert(code.match(/-=/g).length === 3);
```

You should not modify the code above the specified comment.

```js
assert(
  /var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code)
);
```

# --seed--

## --after-user-code--

```js
(function(a,b,c){ return "a = " + a + ", b = " + b + ", c = " + c; })(a,b,c);
```

## --seed-contents--

```js
var a = 11;
var b = 9;
var c = 3;

// Only change code below this line
a = a - 6;
b = b - 15;
c = c - 1;
```

# --solutions--

```js
var a = 11;
var b = 9;
var c = 3;

a -= 6;
b -= 15;
c -= 1;
```