12. The solutions of the quadratic is the roots, so 0 = x^2 -7x -30 = (x-10)(x+3). For this to be satisfied, either x-10 = 0 -> x = 10 and x + 3 = 0 -> x = -3
13. Either x = 0 or x+8 = 0 -> x =-8 for this to be true
18. The GCF of 2, 6, and 20 is 2. No other number satisfies being a common factor.
19. The product of the solutions of the equation is the (constant/leading coefficient) in the quadratic, which is -8/1 = -8
