Let's begin by identifying key information given to us:
Amount invested (Initial Value) = $210 /acre
Gross income (Final Value) = $220 /acre
The percentage return is given by:
[tex]\begin{gathered} Return=\frac{FinalValue-InitialValue}{InitialValue} \\ Return=\frac{220-210}{210}=\frac{10}{210} \\ Return=0.04762\approx4.76\approx4.8 \\ Return=4.8\text{\%} \end{gathered}[/tex]Therefore, the return on investment is 4.8%