Finding the change in y/change in x=the slope, we get
(13-11)/(-4-(-2))=2/-2=-1. Therefore, the equation is y=-1*x+b. Plugging it into (-4, 13), we note that 13=4+b and b=9 by subtracting 4 from both sides, making the equation y=-x+9. Plugging it into A, we get that
1 (y , the second value) = -x+9. Subtracting both sides by 9, we get 1-9=-x and -8=-x. Multiplying each side by -1, we get x=8