Correct Answer is first
1) Doodhwala need to pour milk into 7 litre can and pour it to customer
2) Now Doodhwala has 3 litres of milk and customer has 7 litres of milk
3) Then now Doodhwala will take three litres of milk from customer into 3 litres can and then pour into his own doodhwala can
4) Now customer has 4 litres of milk with him and doodhwala has 6 litres of milk
5) Once gaian Doodhwala will take three litres of milk from customer into 3 litres can and then pour into his own doodhwala can
6) Now customer has 1 litre of milk with him and doodhwala has 9 litres of milk
7) Now doodhwala will take 7 litres of milk into his 7 litre can
8) Then doodhwala will pour 3 litres from 7 litres can into 3 litres can
9) Now 7 litres can will have 4 litres in it and in another 3 litres can he will have 3 litres and in another can he has 2 litres with doodhwala and customer is having 1 litre
10) Now doodhwala will pour 4 litres which is 7 litres into customer
11) As already customer is having 1 litre and now doodhwala has poured 4 litres into customer bowl and now it has become 5 litres