When you want to make a graph to separate things or sizes. E.g. to collect data of people’s shoe sizes and then separate them to see how many people have what size
<h2>Step 1: Solve one of the equations for one of the variables. Let's solve the first equation for y: ...</h2><h2>Step 2: Substitute that equation into the other equation, and solve for x. ...</h2><h2>Step 3: Substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.</h2>