## Chemistry: The Central Science (13th Edition)

$2\times10^1\ mi/gal$
$\frac{400\ km}{47.3\ L}\times\frac{1\ mi}{1.6093\ km}\times\frac{1\ L}{1.057\ qt}\times\frac{4\ qt}{1\ gal}=\frac{19.9\ mi}{gal}\approx2\times10^1\ mi/gal$ estimate $400\div50=8$ $8\div1.6=5$ $5\div1=5$ $5\times4=20$