Question 676198
The answer is C, 28. Here is how I got it: 

If LN = 40, then 40 must equal LM+ MN or 4x-12+x+2.
In other words, 40 = 4x-12+x+2 
Combine and add like terms: 40=5x-10 
Add ten to both sides: 50 = 5x 
Dividing both sides by 5 yields: x=10 

So, once we find x (10), we can substitute it in for LM (or ML). 
4x - 12 
4(10) - 12 
40-12 
28. 

Thus, C is the correct answer.