keeping in mind that an hour is 60 minutes.
[tex]\bf \begin{array}{ccll}
\stackrel{acre}{grass}&\stackrel{minutes}{time}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\frac{3}{8}&45\\
g&60
\end{array}\implies \cfrac{\frac{3}{8}}{g}=\cfrac{45}{60}\implies \cfrac{\frac{3}{8}}{\frac{g}{1}}=\cfrac{45}{60}\implies \cfrac{3}{8}\cdot \cfrac{1}{g}=\cfrac{45}{60}
\\\\\\
\cfrac{3}{8g}=\cfrac{45}{60}\implies 180=360g\implies \cfrac{180}{360}=g\implies \cfrac{1}{2}=g[/tex]