Solve the simultaneous equations: 2x + y = 12; x - y = 6

We add the two equations together (left-hand sides and right-hand sides separately). By doing this we get: 2x + y + (x - y) = 12 + 6. By rearranging and simplifying: 3x = 18.If we divide both sides by 3 we get: x = 6.By substituting the value of x into the second equation we get: 6 - y = 6 which makes y = 0.The solution is x = 6 and y = 0.