Adding and Subtracting Fractions with Unlike Denominators — Process

You and some friends want to play a game of pickup football with another group of friends, but you are not sure if you will have enough people to play. You only have $\frac{3}{4}$'s of a team so you call the other group of friends. They say that is okay because they have $\frac{21}{14}$'s of a team. Do you have enough people for two full teams?