In this video the instructor shows how to add and subtract rational expressions. When you have an addition or subtraction problem of rational expressions, first look and compare the denominator of all the terms. If all of them have the same denominator then the expression can be written as a fraction whose denominator is the original common denominator and whose numerator is the sum of numerators of all the other terms. Simplifying the numerator by adding and subtracting the like terms gives you the result. But if the rational expression does not have a common denominator factor, the different denominators and take a least common multiple of the denominators and solve the expression as shown in this video. This video shows how to solve rational expressions with like and unlike denominators.