Systems of equations are a very useful tool for modeling real-life situations and answering questions about them. If you can translate the application into two linear equations with two variables, then you have a system of equations that you can solve to find the solution.
Here's how it goes:
Step 1: Solve one of the equations for one of the variables. Let's solve the first equation for y: ...
Step 2: Substitute that equation into the other equation, and solve for x. ...
Step 3: Substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.
