# Untitled

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```
public static double CalculateHorseRaceEV(
double backOdds, // Decimal odds for the horse to win
double top3Odds, // Decimal odds for the horse to finish in the top 3
double stake, // The stake amount
double layOdds, // Decimal odds for laying the horse
double commissionRate, // The commission rate for winning lay bets
double underlayFactor // Underlay factor (1 for normal laying, < 1 for underlaying)
)
{
// Calculate the probabilities from the odds
double probabilityWin = 1 / backOdds;
double probabilityTop3 = 1 / top3Odds;
double probability2ndOr3rd = probabilityTop3 - probabilityWin;
double probabilityLose = 1 - probabilityTop3;

// Calculate the potential returns
double payoutWin = stake * (backOdds - 1);
double bonus = stake * 0.8;
double loss = -stake;

// Calculate the lay stake, adjust for underlaying
double layStake = (underlayFactor * stake * (backOdds - 1)) / (layOdds - commissionRate);

// Calculate the returns for lay bet
double layWinProfit = layStake * (1 - commissionRate);
double layLoss = -layStake * (layOdds - 1);

// Calculate the EV considering the lay and back bets
double ev = (probabilityWin * (payoutWin - layLoss)) +
(probability2ndOr3rd * (bonus - layLoss)) +
(probabilityLose * (loss + layWinProfit));

return ev;
}

// Example usage:
// backOdds: 5.0 (4/1 in fractional odds)
// top3Odds: 1.5 (1/2 in fractional odds)
// stake: 50.0
// layOdds: 5.2
// commissionRate: 0.05 (5%)
// underlayFactor: 0.95 (5% underlay)
double expectedValue = CalculateHorseRaceEV(5.0, 1.5, 50.0, 5.2, 0.05, 0.95);

Console.WriteLine(\$"The expected value of the bet is: {expectedValue}");
```