Respuesta :

Answer:

4.5 inches

Step-by-step explanation:

P = 2L + 2W

L = W + 12

P = 2L + 2W

42 = 2L + 2W

42 = 2(W + 12) + 2W

42 = 2W + 24 + 2W

42 = 4W + 24

18 = 4W

4.5 = W