Question 1166459
s = 2lw + 2lh + 2wh


Those coefficients,  21 or 2l ?  Do you understand the trouble there?


As for solving the equation for w, just these possible rules:
(1)  Addition Property of Equality
(2)  Factorization
(3)  Multiplication Property of Equality


{{{w=(s-2lh)/(2L+2h)}}}