In order to solve this problem I simply set up an equation. The equation is 169 = 88 + 7.25h. I put "y" as 169 as it's the goal and "h" represents the hours he works to get his skateboard. Here's how you solve the equation to find "h" to get the number of hours:
1. Move 88 over and subtract- 81 = 7.25h
2. Divide by 7.25 to both sides- 11.17 = h.
I would say that he has to work close to 11.17 hours to meet his goal. Hope this helped :))