A car goes 400 miles on 10 gallons of gas. How many miles can it go on 30 gallons?

If 10 gallons of gas let it travel for 400 miles.....then 3 times as much gas (30 gallons) must let it travel 3 times as far......

First, find the unit rate.400 miles/10 gallons = 40 miles per gallon.

Then, multiply by 30.40 miles times 30 =120 miles and 1 gallon times 30 gallons= 30 gallons.

So, the car can go 120 miles in 30 gallons.