James decides to replace his car.  He sold his $20,000 car for 80% of its value and then was able to haggle to buy a $30,000 sticker price car for 90% of its value.  How much was he out of pocket?
He sold his car for 20000*.8=$<T>multiply(20000, 0.8)=16000.0
He bought the new car for 30,000*.9=$<T>multiply(30000, 0.9)=27000.0
That means he was out of pocket 27,000-16,000=$<T>subtract(27000, 16000)=11000
