Answer:
[tex]\large\boxed{l=\dfrac{P-2w}{2}}[/tex]
Step-by-step explanation:
[tex]P=2(l+w)\qquad\text{use the distributive property}\ a(b+c)=ab+ac\\\\P=2l+2w\qquad\text{subtract}\ 2w\ \text{from both sides}\\\\P-2w=2l\qquad\text{divide both sides by 2}\\\\\dfrac{P-2w}{2}=l[/tex]
