Automatically calculate earnings per win?

Hi guys

As you probably know by now I have set up several sheets to try and help me with the virtual game I play and I am trying to set another one up now.

I am wanting to calculate how much a horse has made profit or loss for each win it gets. So I want to calculate how much it made up to its first win, then from its first to its second win etc. I have attached a file so you can see more clearly what I am hoping to set up.

Thanks
Gemma