# John drove 48 miles and used 2 gallons of gasoline. How many gallons of gasoline will he use if he drives 78 miles?

Jun 16, 2018

$3.25 \text{ gallons}$

#### Explanation:

The ratio of gasoline used to miles drive is (assumed to be) constant.

So if $\textcolor{b l u e}{x}$ gallons are the amount required to drive $78$ miles, then
$\textcolor{w h i t e}{\text{XXX")(color(blue)x" gallons")/(78" miles")=(2" gallons")/(48" miles}}$

color(white)("XXX")rArr color(blue)x" gallons"=(2" gallons")/(48cancel("miles"))xx(78cancel(" miles"))/color(white)1

color(white)("XXXXXXXXXXX")=78/24" gallons" = 3.25" gallons"