The bet would double your money. Bets are placed and broken into, as $2.00 units, (ticket) therefore a $2.00 bet will pay $4.00. So your $100.00 bet will pay $200.00 . A pay-out of that would double your money is called "an even money bet", (short-odds bet). The "even money" bet is a low odds gamble) probability towards winning). For your info. Any time you see a 99-1 odds on the tote board, the pay-out would be VERY HIGH (long-shot bet).