In the Yankee system, you bet on the 6 doubles, the 4 3-folds and 1 4-fold resulting from your selections of a total of 11 bets.
To calculate the winnings of each bet, multiply the stake of each individual bet and not your overall stake amount.
For instance, if your total stake is 55€, the stake of each individual bet will be 5€ (5 x 11 bets = 55€), so you can calculate the amount accordingly.