You can solve systems by using the substitution method. Here are two examples. One says y=3x+2 and the second says 7x-4y=7. The math teacher explains that if y is the same thing as 3x+2, then 3x+2 can be substituted for y in 7x-4y=7. Once it is substituted, your equation will then read 7x-4(3x+2)=7. The next step is to solve for x. Once you have worked out this equation, you will see that x=-3. Finally, your last step is to solve for y. To solve for y, simply substitute x with -3. The equation will read y=3(-3)+2. Y=-7.