Let's denote the length of each width (the two sides) as \( w \).
According to the problem, the total length of all three sides is 6 feet, which includes the back wall (length) and the two widths:
\[ 3.25 + w + w = 6 \]
This can be simplified to:
\[ 3.25 + 2w = 6 \]
Next, we will isolate \( 2w \) by subtracting 3.25 from both sides:
\[ 2w = 6 - 3.25 \] \[ 2w = 2.75 \]
Now, we will divide by 2 to find \( w \):
\[ w = \frac{2.75}{2} = 1.375 \]
Thus, the length of each side (width) is 1.375 feet.