Answer :
368.7 / 18 = 20.48 miles per gallon.....about 20 miles per gallon
miles per gallon means~ miles/gallons
set up the problem just like this ~ 368.7 miles/18 gallons = 20.48 miles/gallon
set up the problem just like this ~ 368.7 miles/18 gallons = 20.48 miles/gallon