John plays at the arcade for 3 hours.  He uses $.50 for every 6 minutes.  How much money did he spend, in dollars?
He was at the arcade for 3*60=<<3*60=180>>180 minutes
So he put coins in 180/6=<<180/6=30>>30 times
That means he spent 30*.5=$<<30*.5=15>>15
#### 15