John cuts his grass to 2 inches.  It grows .5 inches per month.  When it gets to 4 inches he cuts it back down to 2 inches.  It cost $100 to get his grass cut.  How much does he pay per year?
He cuts his grass 4-2=<T>subtract(4, 2)=2 inches
So he gets it cut every 2/.5=<T>divide(2, 0.5)=4.0 months
That means he gets it cut 12/4=<T>divide(12, 4)=3.0 times a year
So he pays 100*3=$<T>multiply(100, 3)=300 per year
