After 56 cans of soup were sold, a clerk moved the remaining cans to a display case. The display case had shelves that could each hold 9 cans. How many shelves were needed to fit all the remaining cans?

We represent the original number of cans of soup by the variable x. After 56 cans of soup were sold, the remaining number of cans of soup is x - 56. Since we have shelves that can hold 9 cans, the number of shelves needed to fit all the remaining cans is

(x - 56) / 9