How to subtract hexadecimal number when one is bigger than the other?

Can someone check my answer? you : )

The measure of an angle is 117°. what is the measure of a supplementary angle?

In order for the function to be linear, what must m be and why? m = 22 because the rate of change is 1. m = 20 because the rate of change is 3. m = 22 because the rate of change is -1. m = 20 because the rate of change is -3.