Make w the subject of the formula?

w = (p - 2L)/2

p = 2w + 2L

p - 2L = 2w

(p - 2L)/2 = w

w = (p - 2L)/2

p=2w+2l
subtract 2l from both sides
p-2l = 2w

divide all terms by 2
p/2 -l = w

flip sides
w = p/2 -l

p=2w+2l
subtract 2l from both sides
p-2l = 2w

divide all terms by 2
p/2 -l = w

flip sides
w = p/2 -l

p=2w+2L
Take away p from both sides
2w + 2L - p = 0
Take away 2w from both sides
2L - = 2w
Divide both sides by 2
(2L - p)/2 = w

p=2w+2L
subtract 2L from both sides
p-2L = 2w

divide all terms by 2
p/2 -L = w

flip sides
w = p/2 -L

2w = P - 2L
w = P/2 - L

1st step
2w=p-2L
w=...

w = p/2 - L

p = 2w + 2L -> = 2(w+L) --> 1/2p = w + L --> w = 1/2p - L