Answer:
12
Explanation:
The triangles are similar because they have the same angles.
Make a proportion to solve for AC which we will substitute with variable x.
AM = MB = 4
AB = AM + MB = 8
BN = NC = 3
BC = BN + NC = 6
big triangle sides: 8, 6, x
small triangle sides: 4, 3, 6
now we can write proportion.
8/4 = x/6
x = 12
AC = 12