Answer:
x=7.5
Explanation:
Begin this by separating the little triangle and the big one.
The little triangle is 8 on one side, then 6 on the other.
The larger triangle is 18 on one side, then 6+x on the other.
Now we can put this into a ratio format, think little triangle to bigger triangle:
8/18 for the left side, then 6/6+x on the right side.
Now cross multiply:
8(6+x)=18(6)
48+8x=108
8x=60
x=7.5