## Using Substitution

Substitution is used when you can easily find the value of one of the variables. This value should not use any complex fractions such as 7/9 or 5/12, because "Well, It just makes it more Complicated"!! Once you find the value of one of the variable, you plug this value in to the other equation. This is where the method of substitution gets its name. After this, you are just left with one variable in the equation you just plugged in the value into. You solve for that one variable. Next, you plug the numerical value that you get for that variable in to the first equation you used. Thus, you are left with one variable in this equation, creating an algebraic problem. Khan Academy can explain this to you using a video: