a car traveled at an average speed of 80 miles per hour for 3 hours and consumes fuel at a rate of 34 miles per gallon

As an example I will finish this problem statement for you:

"A car traveled at an average speed of 80 miles per hour for 3 hours and consumes fuel at a rate of 34 miles per gallon.  How many gallons of fuel will the car use on this trip?

Distance traveled is (80 mph)(3 hrs) = 240 miles.

How many gallons of gas did the car consume?

240 miles        1 gallon
-------------- * -------------- =  7.06 gallons (approx)
        1            34 miles