How do you do elimination, substitution, and graphing

Elimination is something like this:

y= 3x + 20 
y=-3x + 4

=================
y= (take away the x's because you are adding both equations basically) 24

substitution:

y=25
50=25+ y

this might be a bad equation example but you take the y from the top equation and substitute it making the 2nd equation now:

 50=25 + (25)
  50=50
then you do the problem from there

graphing..... I can't help with that, sorry! But I hoped I helped!