John decides to fix a racecar.  It cost $20,000 to fix but he gets a 20% discount.  He wins his first race but only keeps 90% of the money.  The prize is $70,000.  How much money did he make from the car?
He gets a 20000*.2=$<T>multiply(20000, 0.2)=4000.0 discount
So he paid 20000-4000=$<T>subtract(20000, 4000)=16000
He kept 70000*.9=$<T>multiply(70000, 0.9)=63000.0
So he made 63,000-16,000=$<T>subtract(63000, 16000)=47000
,000