```{eval-rst}
:orphan:
```

# Challenge 3
Now, we are putting everything together. Do you remember how to comment? `//` is for a line-comment, where `/*` and `*/` encloses a multi-line comment. Answers will definitely vary, but the below solution works.

```rust
fn main() {

    // 3.
    println(sub(8, 5));

    /* 7. */
    println(sub(17, 9, 1));

    /*
        5.
    */
    println(sub(12, 14, -7, 0));

}
```
Output:
```
3
7
5
```