In this tutorial, we learn how to subtract rational expressions. If they have different denominators, you will first need to get them the same denominator. To do this, you will need to find the lowest common denominator. Factor the denominators that you have and figure out what the lowest common denominator of each of them are. From here, you can simplify the rational expressions in your equations. Next, you can go across the board and subtract the fractions from each other. To finish this up, you will need to find the most simple form of the fraction you got, or else this won't be the right answer.