Answer:
10
Explanation:
I'm pretty sure the segment addition postulate just means that if you add JK and KL together, you'll get the length of JL. Correct me if I'm wrong...
Anyways, JK = 3x - 4, and KL = 5x + 6. If we add these together, according to the segment addition postulate, we will get JL, which equals 9x - 8. So, we set up an equation:
3x - 4 + 5x + 6 = 9x - 8
Simplifying this equation, we get:
8x + 2 = 9x - 8
x = 10
So, our answer is 10.
(also you ask for segment EF but I don't see segment EF so I'm going to just answer the question in the picture)