on a purchase of $ 130 , a store offered a payment plan consisting of a $ 30 down payment and 12 monthly payments of $ 10 each . what percent of the purchase price , to the nearest tenth of a percent , did the customer pay in interest by using this plan ?
12 * 10 + 30 = 150 . ( 30 / 130 ) * 100 = 23.1 answer : c
multiply(divide(subtract(add(multiply(10, 12), 30), multiply(10, 12)), 130), const_100)