Bob and Jim decide to skip rocks.  Bob can skip a rock 12 times.  Jim can skip a rock 15 times.  If they each skipped 10 rocks how many total skips did they get?
Bob got 12*10=<T>multiply(12, 10)=120 skips
Jim got 15*10=<T>multiply(15, 10)=150 skips
So in total they got 120+150=<T>add(120, 150)=270 skips
