Ok, without the equations, I will try to make this as encompassing as possible. Say you have an equation of 4x+y=16 & 12x+4y=52, you can solve these with "simple substitution."

To do this type of problem, you pick one of these equations and solve it for one of the equations. I will take the first equation and solve it for y.

Doing this leaves y=16-4x.

Now plug this into the second equation and replace the "y" with "16-4x" and solve for x to get a numerical value.

Ex:

12x + 4(16-4x) = 56

12x + 64 - 16x = 52

-4x = -12

x=3

Now you take this "x=3" value and plug it into the other equation and solve for y.