Explanation

To determine the total number of fence poles used, we need to consider that each corner pole is counted twice when calculating the poles for each side.

Each side of the square plot has 27 poles.

Since the plot is square, it has 4 sides.

First, calculate the total number of poles if we didn't account for the corners:

27 poles/side×4 sides=108 poles

However, this calculation counts each corner pole twice.

A square has 4 corners, so we need to subtract the 4 extra poles that were counted twice:

108 poles−4 extra poles=104 poles