How Do You Know When You Need To Cross Multiply With Fractions?

The simple way to solve fractions in multiplication is to multiply the numerators of the fractions to get the new numerator and multiply the denominators of the fractions to get the new denominator. You only need to cross multiply the fractions when they are on the opposite side of a equation. The example is;

3/5=1/2
you will get 6/5 from cross multiplication.