Answer:
X=14
Step-by-step explanation:
If you measure them, they'll be very close to the same length.
Also, the triangles are very similar. Given this information, a simple way to solve it is:
12-4=8 so to find X subtract 4 from 18.
18-4=14 so X=14
I hope my brain did the correct math for you.
It probably didn't, but I tried.