sub in 2x + 3 for y in the first equation
2x - (2x + 3) = 7...now distribute the - through the parenthesis
2x - 2x - 3 = 7 ...add 7 to both sides
2x - 2x = 7 + 3
0 = 10 (incorrect)
This system has no solution....that is because the lines are parallel and will never intersect