The task is to generate the correct answer for a given math problem.
--------
Question: Problem: a jar contains a mixture of ab in the ratio 4 : 1 . when 40 l of mixture is replaced with liquid b , ratio becomes 2 : 3 . how many liters of liquid a was present in mixture initially .

Answer: 64


Question: Problem: the average of first 17 even numbers is ?

Answer: 18


Question: Problem: if ( 5 + k ) ( 5 - k ) = ( 5 ^ 2 ) - ( 2 ^ 3 ) , then what is the value of k ?

Answer:
2