3x + 4y = 38 ( equation 1) ----> ×5 5x - 5y = -30 ( equation 2) ----> ×3 When you multiply eqn 1 by 5 you get, 15x + 20y = 190 And when you multiply eqn 2 by 3, you get, 15x - 15y = -90 Then you solve both equations by subtracting eqn 2 from eqn 1 15x + 20y = 190 15x - 15y = 90 Then 15x - 15x gets cancelled and 20y - (-15y) gives 35y and 190 - (-90) gives 280. So that gives 35y = 280 y = 8 And when you replace y = 8 in any of the two equations, x = 2