bet 4 to win

[excited]

does anybody know how to bet 4 horses per race to win $100 profit per race

[Mr. Logic]

I imagine books dealing with Dutch book betting might cover this.
The big disadvantage of betting any number of horses just to win a set amount each race is you do not have a big collect when you back longshots.
Also a losing run of just a couple of races really sets you back.