What is something that multipys to 72 and adds - 27?

24 if you look at a factor tree, - 24 x - 3 = 72 and - 24 + - 3 = - 27

You want xy=72 and x+y=-27. Now solve for either x or y in one of the equations and then substitute it into the other equation. For instance, x=-27-y so you can substitute to get (-27-y) y=72. Distribute so - 27y-y^2=72. let's move everything to one side so 0=y^2+27y+72. Now use quadratic formula to solve.