If a car gets 42.1 mpg on the highway, how many gallons of fuel will it use by traveling 340 highway miles? (round answer to tenths)

For 1 gallon of fuel, car travels = 42.1 miles
Then, for 340 miles, it will need = 340 / 42.1 = 8.076 gallon

After rounding-off to the nearest tenth it will be 8.1 gallons.

In short, final answer of your question would be 8.1 gallons

Hope this helps!