3x - 4y = 8 AND 9x + 4y = 4, solving by elimination

Question

when I was solving this I think I messed up but I can't find my mistake, and it seems like I did it smoothly, can someone do a step-by-step so I can find my mistake?

Answer 1

3x - 4y = 8

9x + 4y = 4

Add the 2 equations to eliminate y and get

12x = 12

x = 2

Plug x=2 into either equation and solve for y.