+125: Risking $250.00 wins $312.50
-108: Risking $287.00 Wins $275.96
Total risk: $537.00
Expected profit: $25.75
If scratched, the $287 pushes and you lose $250.
So really, the most you lose is $250 if the horse gets scratched and if he does not get scratched, you win $25.75. Pretty good deal I would say.