I'm trying to get my head around this but can someone tell me if this is correct.

If i lay a horse for $5 @ $3.50 and it wins all i pay out is $12.50? if it loses i make $5?

So if i have 10 lay bets all at $5 and 1 wins at $3.50 i would make $32.50?

This might seem stupid but i want to double check before i start laying nags. I find more losers then winners lol.

Thanks in advance.

I forgot about the %5 commis. So it would be $32.50 - $2.25com = $30.25?

You are correct on both counts