so 13- 7 and 1/2
I can't draw a number line here but I'll try to help
so 13 (count 13 lines to the right (positive) and put a dot there to mark that)
then -7 and 1/2
so from the 13 point, move 7 and 1/2 spaces to the left (negative) and get the dot at 5 and 1/2