John is trying to save money by buying cheap calorie-dense food.  He can buy 10 burritos for $6 that have 120 calories each.  He could also buy 5 burgers that are 400 calories each for $8.  How many more calories per dollar does he get from the burgers?
The burritos have 10*120=<T>multiply(10, 120)=1200 calories
That means he gets 1200/6=<T>divide(1200, 6)=200.0 calories per dollar
The burgers get 5*400=<T>multiply(5, 400)=2000 calories
So he gets 2000/8=<T>divide(2000, 8)=250.0 calories per dollar
So he gets 250-200=<T>subtract(250, 200)=50 more calories per dollar from the burgers
