Answer:
D. 11
Explanation:
Take the two horizontal line measurements and subtract them.
13-9=4
That is how much it changed between these two numbers. Since x is exactly halfway between, simply divide 4 and 2.
4/2=2
Now, add that to 9 or subtract it from 13.
9+2=11
or
13-2=11.
Hope this helps!
If not, I am sorry.