Discount

A 20% discount means that the volleyball just sold for 80% of its normal cost....so

35 * .80   = $28          [the discount was $7 ]

You can use proportions. x     =     20

                                         35         100

You multiply 35 and 20, which gives you 700, and divide it by 100, so you get $7 discount, to get the total of the volleyball price after the discounted price, you subtract. 35-7= 28