To solve this problem we can use proportion, but first its nice to transform our fraction into improper fraction, so
\(83 \frac{7}{10}= \frac{837}{10}\)
andÂ
\(2 \frac{1}{4}= \frac{9}{4}\)
Now we can make proportion
\(\frac{837}{10}\)--------------------------\(\frac{9}{4}\) of fuel
x-----------------------------\(1\)
Now we can cross multiply
\(x= \frac{ \frac{837}{10} }{ \frac{9}{4} }= \frac{837}{10}* \frac{4}{9} = \frac{3348}{90}=37.2\) - its the result