A box trifecta bet allows you to select as many runners as you like to finish first, second and third (in any order). Use the list below to calculate the costs of aR$1 unit box trifecta on the Melbourne Cup (halve if using a 50-cent unit):

The +  and -  are put in front of odds or lines, indicating the favorites and underdogs. The favorites will be marked with a minus sign, whereas underdogs have the plus sign. This is the case for all types of bets, including moneylines and point spreads.

The payout odds for a bet on a single number is 35 to 1. This is odds of winning 1:35. This pays based on a probability of winning P_Win = A / (A + B) = 1 / (1 + 35) = 1/36 = 0.02778 or 2.778% (97.22% Losing). The true odds of winning are based on 38 outcomes.

When you see the odds presented as 30:1 or 3:1 that's actually just showing the payout for a winning bet, not the likelihood of that team winning. 30:1 doesn't mean that the team is 30x more likely to win, it means that if you bet on that team and they win you will receive $30 for every dollar you bet.