I think you meant (1/2)x+9=13
Note: the parentheses are only around the 1/2 because I can only type it horizontally (left to right, not up and down like it probably is on your paper)
8 is a solution to (1/2)x+9=13.
If you plug in x=8, you get one-half times 8 plus 9. One-half times 8 is 4, and 4 plus 9 is 13. I hope that helped. :)