When we subtract equations we subtract the left sides, subtract the right sides, and set them equal. I'll show detailed steps but usually you can just do it all in one step.
5x + 4y = 25
5x + 2y = 3
Subtracting,
5x + 4y -(5x + 2y) = 25 - 3
2y = 22
The problem is easily solved from here, but let's call it done with
Choice B