It doesn't matter which x and y coordinates we use as x1 and x2 as long as we are consistent with both. Since the x component in the slope = 3, we can see that they used 7-4, so for the y component we will use w - (-6)
w-(-6) = 4 (we set it to 4 because of the slope) w+6 = 4 w = 4-6 w = -2
