I'll solve B, and then challenge you to do A and C on your own!
If the line passes through (-3,4) and (5, -4), then the slope is the change in y over the change in x, which is (4-(-4))/(-3-5)=8/-8=-1 in this scenario, meaning that in the equation y=mx+b (with m as the slope), we have y=-x+b so far.Note that we only have to find b, as y and x can stay as variables. Plugging (-3,4) in for y and x (to find B), we get 4=-(-3)+b=3+b. Subtracting 3 from both sides, we get b=1 and the equation being y=-x+1
