**Tell us what’s happening:**

from the examples in the last task i answered the question however i dont understand one bit of it

x.sort((a,b) => a - b) - what is thr - actually symbolising here? a minus b or just a comes before b?

```
**Your code so far**
function nonMutatingSort(arr) {
// Add your code below this line
let x = globalArray.concat(array)
x.sort((a,b) => a - b)
return x
```

**Your browser information:**

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:67.0) Gecko/20100101 Firefox/67.0`

.

**Link to the challenge:**

https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/functional-programming/return-a-sorted-array-without-changing-the-original-array