James paints a 20 ft by 15 ft mural.  It takes him 20 minutes to paint 1 square foot and he charges $150 per hour.  How much does he charge to paint the mural?
The mural is 20*15=<T>multiply(20, 15)=300 square feet
So it takes him 300*20=<T>multiply(300, 20)=6000 minutes
So he paints it in 6000/60=<T>divide(6000, 60)=100.0 hours
That means he charges 100*150=$<T>multiply(100, 150)=15000
