Need help with a quick math question?

The question is 5(x+2y)=20 where x=2, y=? Can that question be solved by doing this: 5(2+2y)=20 (I replaced X with 2) 5(4y)=20 (I added 2+2) 5•4=20 (I multiplied) 1•20=20 therefor Y is 1? (I dunno what I did here.) I never done this kind of math before, so sorry if I got it wrong. If I got it right ,which I highly doubt I did, why does Y=1?