plmnpler

the finance charge is on the remainder of the cost, not on the downpayment of the cost as suggested by your answer

50000*0.2+50000*0.8*1.4- (40000*0.2+40000*0.8*1.4)

= 50000*(0.2+1.12)-40000*(0.2+1.12)

= (50000-40000)*1.32

= 13200