[tex]\begin{array}{ccll} miles&gallons\\ \cline{1-2} 350 & 20\\ 875& g \end{array} \implies \cfrac{350}{875}~~=~~\cfrac{20}{g} \\\\\\ \cfrac{2}{5}=\cfrac{20}{g}\implies 2g=100\implies g=\cfrac{100}{2}\implies g=50[/tex]
