P=2 (l+b) solve for l

p=2 (l+b)

multiply the bracket by 2

(2) (l) = 2l

(2) (b) = 2b

p=2l+2b

move 2b to the other side

sign changes from + 2b to - 2b

p-2b=2l+2b-2b

p-2b=2l divide both sides by 2

p/2-2b/2=2l/2

cross out 2 and 2 for - 2b/2 = 1*-1*b=-b

cross out 2l and 2 = 1*1*l=l

p/2-b=l

answer:

1=p/2-b