Respuesta :

add 15 to both sides (15&57)
15 cancels out so then you just add 15 and 57 and you get 72
now you divide 57 by 8 and you get 7.125

w = 7.125
8w - 15 +57 = 0
8w -15 = -57
8w = -42
8w/8 = -42/8
w = -5.25

(Sorry if I didn't show the work very well.)