What is the sum of all possible values of x such that 2x(x - 10) - x(x - 5) = -50?
2x^2 - 20x -x^2 + 5x = -50 simplify
x^2 -15x + 50 = 0 factor (or use Quadratic Formula)
(x-10)(x-5) = 0
x = 10 or 5 add 'em......
