John rents a car to visit his family.  It cost $150 to rent the car.  He also had to buy 8 gallons of gas to fill it up and gas is $3.50 per gallon.  The final expense is $.50 per mile.  If he drove 320 miles how much did it cost?
The gas cost 8*3.5=$<<8*3.5=28>>28
The mileage expenses cost 320*.5=$<<320*.5=160>>160
So in total he paid 150+28+160=$<<150+28+160=338>>338
#### 338