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 $100 to get his grass cut.  How much does he pay per year?
He cuts his grass 4-2=<<4-2=2>>2 inches
So he gets it cut every 2/.5=<<2/.5=4>>4 months
That means he gets it cut 12/4=<<12/4=3>>3 times a year
So he pays 100*3=$<<100*3=300>>300 per year
#### 300