Respuesta :

13 - b/6 = 2 - 0.125b
78 - b = 12 - 0.75b
78 = 12 - b + 0.75b
78 = 0.25b + 12
78 - 12 = 0.25b
66 = 0.25b
66/0.25 = b
b = 264