There is no solution.
Explanation:
Given:
y = 2x + 1
4x - 2y = 4
Substitute y = 2x + 1 into 4x - 2y = 4
4x - 2(2x + 1) = 4
4x - 4x - 2 = 4
0x = 4 + 2
0x = 6
Anything to the multiple of zero is zero. Hence 0x = 0, and 0 ≠ 6
So there is no solution to the equation.