Tom paints a room that has 5 walls.  Each wall is 2 meters by 3 meters.  John can paint 1 square meter every 10 minutes.  He has 10 hours to paint everything.  How many hours does he have to spare?
Each wall is 2*3=<T>multiply(2, 3)=6 square meters
So each wall takes 6*10=<T>multiply(6, 10)=60 minutes to paint
So it takes 60/60=<T>divide(60, 60)=1.0 hour to paint each wall
That means in total it takes 5*1=<T>multiply(5, 1)=5 hours to paint
So he has 10-5=<T>subtract(10, 5)=5 hour left after finishing painting
