Answer:
Explanation:
This is a ratio problem using triangles. 8 and x are part of the smallest triangle at the top. The next triangle down has a side length of 8 + 9 which is 17, and the other side length of x + 12. So we proportion the problem like that:
Then cross multiply to get
8(12 + x) = 17x and
96 + 8x = 17x and
96 = 9x so
x = 10.666666
or 10.7
The last choice in the list.