Answer:
[tex]l = \frac{A - w}{2}[/tex]
Step-by-step explanation:
Given A = 2(l + w)
Divide both sides by 2:
[tex]\frac{A}{2} = \frac{2(l + w)}{2}[/tex]
A/2 = l + w
Subtract w from both sides to isolate l
[tex]\frac{A - w}{2} = l + w - w[/tex]
[tex]l = \frac{A - w}{2}[/tex]