Answer:
AC = 12
Step-by-step explanation:
We can use proportions to solve. Put the smaller triangle side over the larger triangle side
AB AC
--------- = --------
AD AE
Substituting what we know
8 AC
--------- = --------
8+10 AC+15
Using cross products
8 *(AC+15) = (8+10)*AC
Simplify
8 *(AC+15) = (18)*AC
Distribute
8AC +120 = 18AC
Subtract 8AC from each side
8AC-8AC +120 = 18AC -8AC
120 =10AC
Divide each side by 10
120/10 = 10AC/10
12=AC
