Jan buys 5 dozen roses.  Each rose cost $6.  Since he bought so many he only needs to pay 80%.  How much did he pay?
He got 5*12=<T>multiply(5, 12)=60 roses
So the cost was 6*60=$<T>multiply(6, 60)=360
So he has to pay 360*.8=$<T>multiply(360, 0.8)=288.0
