The solution of x = y + 5,2x-y = 7 is a solution of the binary linear equation x + y + a = 0. Find the value of A

The solution of x = y + 5,2x-y = 7 is a solution of the binary linear equation x + y + a = 0. Find the value of A

2 (y + 5) - y = 7, y = - 3, x = - 3 + 5 = 2 - 3 + 2 + a = 0, then a = 1