Someone please help me with two answer choices

Which of the following contains a variable?

Agroup of three friends order a combo meal which includes two slices of pizza and a drink each drink is priced at $2.50 the combined total of $31.50 how much is the cost of a slice of pizza

Johnny rode his bike to a friends house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was unable to play. what was his displacement for the total bike ride trip? what could you use as a reference point ? show the steps to solve this problem.