How do you use substitution to solve the system of equations?

With this type of math, you have two equations to start with. You will solve for one variable (either x or y) in one equation. Take that answer and substitute it in the other equation to solve for a number. Once you have the number for either x or y (whichever you chose to solve for), take that number and plug it in to the equations to solve for the other variable.

Example:
2x-3y=2
4x+y=16

Let's solve for x in the first equation:
2x-3y=2
Add 3y to both sides
2x=2+3y
Divide both sides by 2
x=(2+3y) / 2

Now take this answer and substitute it for x in the second equation:
4x+y=16
4((2+3y)/2) +y = 16
[(4*2)+(4*3y)]/2=16
(8+12y) / 2=16
Two goes into each of the numerators
4+6y=16
Subtract 4 from both sides
6y=12
Divide both sides by 6
y=2

Now substitute y=2 back into one of the original equations to solve for x.

4x+y=16

4x+y=16
4(2)+y=16
8+y=16
Subtract 8 from both sides
y=8

Hope this helped!! :)