James builds a 20 story building.  The first 10 stories are each 12 feet tall each.  The remaining floors are each 3 feet taller.  How tall is the building?
The first 10 floors are 10*12=<T>multiply(10, 12)=120 feet
There are a remaining 20-10=<T>subtract(20, 10)=10 stories
They are each 12+3=<T>add(12, 3)=15 feet
So those stories are 15*10=<T>multiply(15, 10)=150 feet
So the total height is 120+150=<T>add(120, 150)=270 feet
