Find two numbers whose sum is 35 and whose difference is 9?

Answer 1

start with what you know: x + y = 35 x - y = 9 add them together: x + x + y - y = 35 + 9 resolve the rest of the facts: X + X = 44 X = 22 22 + y = 35 22 + y - 22 = 35 - 22 y = 13 confirm: 22 + 13 = 35 22 - 13 = 9