To find out how many acres Ms. Green planted with potatoes, we need to calculate \( \frac{3}{4} \) of 30 acres.
The calculation is as follows:
\[ \frac{3}{4} \times 30 = \frac{3 \times 30}{4} = \frac{90}{4} \]
Now, we can simplify \( \frac{90}{4} \):
\[ \frac{90}{4} = 22.5 \]
So, Ms. Green planted \( \frac{90}{4} \) acres or 22.5 acres with potatoes.
Among the provided responses, the correct one is:
90/4 or 22.2/4 acres.
(Note: The formatting of the answer with "22.2/4" is likely a typographical error; it should correctly state "22.5/4.")