Alexis bought x boxes of cereal for $3 each, including tax, and paid with a $20 bill. what is the expression for the change he got back?

Volcanic eruption, but i dont know the best answer. because i am natursl science student

A)26•2=52there are 2 sides with the same length116-52=64the other 2 side have to be half of 64 each64/2=32the width is 32b)make two sentences about these steps because your teacher knows how you write and explain things.