Gentry assembled a new 24 foot round pool in her backyard.  To fill the pool with water, she used four hoses.  Two of the hoses each deliver water at a rate of 2 gallons per minute.  The other two hoses each deliver water at a rate of 3 gallons per minute.  With a volume of 15,000 gallons, how many hours will it take to fill the pool?
Each of the two hoses delivers water at a rate of 2 gallons per minute, for a combined total of 2*2=<T>multiply(2, 2)=4 gallons of water per minute.
The other two hoses each deliver water at a rate of 3 gallons per minute, for a combined total of 2*3=<T>multiply(2, 3)=6 gallons of water per minute.
Thus, all four hoses deliver a combined total of 4+6=<T>add(4, 6)=10 gallons of water per minute.
With a volume of 15,000 gallons, it would take 15,000/10=<T>divide(15000, 10)=1500.0 minutes to fill the pool.
Converting to hours, it will take 1500/60=<T>divide(1500, 60)=25.0 hours to fill the pool.
