bearing in mind that, there are 3.78 Liters in 1 US gallon, then, how many gallons in 70 liters?
[tex]\bf \begin{array}{ccllll}
liters&gallons(US)\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
3.78&1\\
70&g
\end{array}\implies \cfrac{3.78}{70}=\cfrac{1}{g}\implies g=\cfrac{70\cdot 1}{3.78}[/tex]