Answer:
[tex]l = \frac{a}{2w} - \pi[/tex]
Step-by-step explanation:
Assuming...
[tex]a = 2\pi \: w + 2lw[/tex]
factor 2w out and divide both sides by 2w
[tex]a = 2w(\pi + l)[/tex]
[tex] \frac{a}{2w} = \pi + l[/tex]
subtract both sides by π
[tex]l = \frac{a}{2w} - \pi[/tex]