The perimeter of a rectangle is given by the formula P = 2W +2L, where w is the width and l is the length. We arrange the formula for the length(l).

To find:
The formula for the length, l, of the rectangle.
Solution:
The perimeter of the rectangle is given by P = 2w + 2l.
Now, we have to isolate l and solve:
[tex]\begin{gathered} P=2w+2l \\ P-2w=2l \\ \frac{1}{2}P-w=l \end{gathered}[/tex]Thus, the first option is correct.