Darin spent $8.40 for gasoline. He saw gas priced at $1.40/gal and $1.60/gal. How many gallons could he have bought at either place?

This was a simple division problem:  At the place where they sold gasoline for $1.40/gallon, he could have bought:  $8.40 / $1.40 = 6 gallons of gasoline  At the place where they sold gasoline for $1.60/gallon, he could have bought:  $8.40 / $1.60 = 5.25 (5 1/4) gallons of gasoline.