-5x - 2y = 7 (1) 7x + y = -8 (2) Express y from the equation (2): y = -7x - 8, and substitute it into the equation (1). You will get one single equation for x: -5x - 2(-7x - 8) = 7. Simplify and solve it: -5x + 14x + 16 = 7, 9x = 7 - 16 = -9, x = -1. Now substitute the found value x = -1 into equation (2) and find y: -7 + y = -8 -----> y = -8 + 7 = -1.