Question

How many miles would it take for one gallon if 140 miles took 7 gallons

Answer 1

`\begin{array}{ccc}7\ gallons&-&140\ miles\\1\ gallon&-&x\ miles\end{array}\qquad|\text{cross multiply}\\\\7x=140\qqiad\text{divide both sides by 7}\\\\\boxed{x=20}`

Answer 2

140 miles / 7 gallons = 20 miles per gallon

this means you can go 20 miles using 1 gallon