You can drive your car 21.7 miles with one gallon of gasoline. At that rate, how many miles can you drive with 13.2 gallons of gasoline?

1 Answer
Apr 9, 2017

#286.4# miles


This is a useful practical application of algebra! It is a ratio – something that can be used for comparisons or conversions. We set it up as a dimensional fraction to see how it works.

We have #((21.7 "miles")/(1 gallon))# as the ratio. We have a similar ratio with an unknown part:

#(("? miles")/(13.2 gallons))# Putting them together algebraically we can find the desired value and units.

#((21.7 "miles")/(1 gallon))# = #(("? miles")/(13.2 gallons))#

#("? miles") = (13.2 gallons) * ((21.7 "miles")/(1 gallon)) = 286.4# miles