State the slope of the line in simplest form.

If x increases by 2 from -2 to 0, y increases from 0 to 2.

The slope is defined as rise / run, which in this case is   2-0
                                                                                        = 2/2 = 1.
                                                                                          0-[-2]

I wouldn't bother with this subtraction for this particular problem.  I'd just notice that if the run is 2, the rise is 2, and thus the slope is 2/2 = 1.