Answer :
Answer: [tex]l=\dfrac{P}{2}-b[/tex]
Step-by-step explanation:
P = 2(l + b)
Divide both sides by 2:
[tex]\dfrac{P}{2}=l+b[/tex]
Subtract b from both sides:
[tex]\dfrac{P}{2}-b=l[/tex]
Note: You can also multiply b by [tex]\frac{2}{2}[/tex] if you want the left side to be one fraction.
[tex]\dfrac{P}{2}-\bigg(\dfrac{2}{2}\bigg)b=l\\\\\\\dfrac{P-2b}{2}=l[/tex]