Answer:
The area for a rectangle is calculated by multiplying its length and width. You are given the area and one side, so you can set up an equation and solve for the other side.
Explanation:
A = 12 sq. mi.
L = 23 mi.
W = ?
A = L x W, so 12 = 23 x W
Solve for W by dividing both sides by 23.
W = 12/23 mi.
You can't reduce that fraction any further.
Just as a side note, the answer tells us that the park is long and narrow. It is 23 miles long, but just over half a mile wide.