Respuesta :

multiply by 8 on both sides

(20)8 - 8(4b/8) = (18)8

160 - 4b = 144

subtract 160 on both sides

160 - 160 - 4b = 144 - 160

-4b = -16

divide by -4 on both sides

-4b/-4 = -16/-4

b = 4