Jenny filled 12 pitchers with an equal ammount of lemonade. in the 12 pitchers was 41.4 liters. how many liters would be in 7 pitchers ?

In the question it is already given that the 12 pitchers filled by Jenny has equal amount of lemonade. Also there are several information's of immense importance already given in the question. Based on those information's the answer to the question can be easily determined.
The amount of lemonade in the 12 pitchers = 41.4 liters
So
The amount of lemonade in 1 pitcher = (41.4/12) liters
Then
The amount of lemonade in 7 pitchers = (41.4/12) * 7 liters
                                                              = 289.8/12 liters
                                                             = 24.15 liters
So 2415 liters of lemonade will be there in 7 pitchers.