STEPS TO GET THE CORRECT ANSWER:
First write your question like this:
{ ( [9x] [-31/8] ) - ( [7x] [+13/8] ) }
2: You need to subtract 9x and 7x from (9x-31/8)-(7x+13/8) you get 2x. So now you know that the answer has 2x. Eleminate A) and D).
3: Then need to subtract -31/8 from +13/8. You get -11/2.
Turn -11/2 into a mixed number you will get -5 1/2.
4: Put 2x and -5 1/2 together and you would get 2x-5 1/2
But answer C.) is closest to 2x-5 1/2 so the answer is
ANSWER: C.) 2x-4 1/2