now, recalling that for 1 yard, there are 3 feet, therefore [tex]\bf \begin{array}{ll}
yards&feet\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
1yd&3ft\\
(1yd)^2&(3ft)^2\\
yd^2&3^2ft^2\\
&9ft^2
\end{array}[/tex]
and keeping in mind that, there are 4840 yd² in 1 acre, then
[tex]\bf \cfrac{\quad \frac{3}{4}~\underline{acre}\quad }{80000~\$}\cdot \cfrac{4840~\underline{yd^2}}{\underline{acre}}\cdot \cfrac{9~ft^2}{\underline{yd^2}}\implies \cfrac{\frac{3}{4}\cdot4840\cdot 9~ft^2}{80000~\$}\implies \cfrac{\frac{130680}{4}}{80000}
\\\\\\
\cfrac{\frac{130680}{4}}{\frac{80000}{1}}\implies \cfrac{130680}{4}\cdot \cfrac{1}{80000}\implies \cfrac{3267}{8000}~\frac{ft^2}{\$}~\approx~ 0.408375 ~\frac{ft^2}{\$}[/tex]