Respuesta :

Step-by-step explanation:

Since B is the midpoint of AC. So,

AB = BC

12x - 12 = 4x + 28

12x - 4x = 28 + 12

8x = 40

x = 40/8

x = 5

Now,

AB = BC = 4(5) + 28

= 20 + 28

= 48 cm

Now

AC = AB + BC

AC = 48 + 48

AC = 96 cm