Solve the following simultaneous equations: 2x + y = 17, x - y = 4

2x + y = 17 x-y = 4 ---> x = 4 + y2(4+y) + y = 17 ------> 8 + 2y + y = 17 -----> 8 + 3y = 17 --------> 3y = 9 -----> y=3 x = 4+y ------> x = 7