Question

If 13x+7y and 7x+13y=45 then x-y= how to solve quickly

Answer 1

$given \\ 13x + 7y = 45 - - - (1) \\ 7x + 13y = 45 - - - (2) \\ (1) - (2) \: \: gives \\ 6x - 6y = 0 \\6(x - y) = 0 \\ x - y = 0$