at a certain supplier , a machine of type a costs $ 20000 and a machine of type b costs $ 60000 . each machine can be purchased by making a 20 percent down payment and repaying the remainder of the cost and the finance charges over a period of time . if the finance charges are equal to 40 percent of the remainder of the cost , how much less would 2 machines of type a cost than 1 machine of type b under this arrangement ?