Okay so in order to find your slope you're going to need to label your first set of coordinates! Since you know that -6 is X, you're going to label it X(subscript 1) and since you know that 7 is Y, you're going to label it Y(subscript 1).
You're going to want to do the same thing with the other set of coordinates as well. -6 will be X(subscript 2) and -2 will be Y(subscript 2).
Then you need to set the labeled coordinates up in the following formula:
m=y(subscript 2) - y(subscript 1) / x(subscript 2) - x(subscript 1)
and then solve for your slope!