Cameron used 12 gallons of gas to drive 240 miles in 4 hours.

how fast was he driving in miles per hour? and what was his gas mileage in miles per gallon?

The first thing you can find out is how many miles per hour he was driving, you divide 240 by 4 to get 60mph. From there you will take 240 and divide by 12 to get 20 mpg. So his car gets 20 miles per gallon and he is driving 60 miles per hour.