To find the percentage of the land that is available for farming, you can use the formula:
\[ \text{Percentage} = \left( \frac{\text{Farmed Land}}{\text{Total Land}} \right) \times 100 \]
In this case, the farmed land is 20 acres, and the total land is 30 acres.
\[ \text{Percentage} = \left( \frac{20}{30} \right) \times 100 = \left( \frac{2}{3} \right) \times 100 \approx 66.67% \]
Therefore, the percentage of the land that is available for farming is approximately 66.67%.
Among the provided options, the closest match is 66.66¯¯¯¯¯ %.