recall that one whole is 1, or in this case since the denominator is 4, then 4/4 is 1 whole, so the whole lawn is 4/4.
[tex]\bf \begin{array}{ccll}
gallons&mowed\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\frac{1}{2}&\frac{1}{4}\\\\
g&\frac{4}{4}
\end{array}\implies \cfrac{\frac{1}{2}}{g}=\cfrac{\frac{1}{4}}{\frac{4}{4}}\implies \cfrac{\frac{1}{2}}{\frac{g}{1}}=\cfrac{\frac{1}{4}}{\frac{4}{4}}\implies \cfrac{1}{2}\cdot \cfrac{1}{g}=\cfrac{1}{4}\cdot \cfrac{4}{4}
\\\\\\
\cfrac{1}{2g}=\cfrac{1}{4}\implies 4=2g\implies \cfrac{4}{2}=g\implies 2=g[/tex]
