Question 331683
x + y = 20 ___ y = 20 - x


substituting ___ x^2 + (20 - x)^2 = 218 ___ x^2 + 400 - 40x + x^2 = 218


x^2 - 20x + 91 = 0 ___ (x - 13)(x - 7) = 0


x = 13 (or 7) and y equals the other one