### Subtraction in Logic

This problem uses the Logic starter file located here.

Write facts to define subtraction. You may use anything already included in the starter file linked above.

```
(fact (sub ; YOUR CODE HERE ))
```

```
(fact (sub ?x ?y ?z)
(add ?z ?y ?x))
```

Here, we only need to define one fact because the base case is caught by in `add`

. Subtraction is just addition with the arguments switched around so instead of x - y = z, we just manipulate it such that we have z + y = x.

I don't claim to be perfect so if you find an error on this page, please send me an email preferably with a link to this page so that I know what I need to fix!