Rational Expressions can have polynomials in the numerators and denominators. They can be multiplied and simplified. We apply the rule of factoring (GCF, trinomials, difference of squares) to factor the polynomials. Then, if we have common factors in the numerators and denominators, we can cancel them out because they actually divide out to 1. Marcos and I worked through many examples, and had fun "cancelling" the common factors with much gusto!