A car has a rating of 3.5 gallons per 100 miles. Determine the miles per gallon (mpg) rating for this car. (Enter a number. Round your answer to two decimal places.)

A second car has a rating of 4.1 gallons per 100 miles. Determine the mpg rating for this car. (Enter a number. Round your answer to two decimal places.)

I do not really need the second question answered just need to know how to do at least one of them, so I can figure it out!