Question

Find the value of two numbers if their sum is 20 and their difference is 2

Answer 1

$x+y = 20 \\ x - y = 2 \\ x = y + 2 \\ and = > x + y = 20 \\ y + 2 + y = 20 \\ 2y = 20 - 2 \\ y = 9 \\ x = 11$