You want to start with breaking down -40 to find the integers that will go into that, which are 8 and 5. Then you take the knowledge of 8 and 5 and turn your attention to -3x.
8 and 5 must be added together to equal -3x. 8 is the larger number so it must be the negative in the equation and be must be the positive. Thus it would be -8x + 5x = -3x
Knowing that, is it simple to break x^2 because it is simply x * x = x^2
