I'm in 7th grade and I learned in chapter 2 that if there is two negatives (ex: 9 - - 2) you have to make the two negatives a positive, this is called "add a line, change the sign" therefore my example would equal 11. Your question
9 - (- 1/2) would actually be 9 + (+1/2) it's that easy
So the answer would be 9 1/2 ( positive)
I hate math but that's one of my fav tricks!