I did a few problems like
x + y = 3
x - y = 5
but I can't figure out how to do this one because they don't line up and when you make them line up the x's or the y's don't cancel out. I'm stuck. : /

y = 1 + 2x
5x - 2y = 18

Yes, they would do if you know what to do.

y = 1 + 2x
5x - 2y = 18

Okay, you can move the 'y' in the first to the right and the '1' to the left giving:
-1 = 2x - y

right?

Okay, you can write it this way too:
2x - y = -1

Now, I'll put them one under the other to see what has to be done.
2x - y = -1
5x - 2y = 18

If you want to eliminate y, you need 2y and 2y, or y and y only. It's easier to make them 2y and 2y. So, multiply the first equation by 2 throughout.

2(2x - y) = 2(-1)

Notice that if you expand, you get:

4x - 2y = -2

and from the beginning, you had:

5x - 2y = 18

Now, you can solve by elimination.
4x - 2y = -2
5x - 2y = 18

Is it OK? :)