Answer:
Option B
Explanation:
Amountof milk=81 l
13 of whole milk =813=27l
Quality of milk left after first operation =81-27=54
Again amount of water =543=18
Quality of milk left after 2nd opertaion =54-18=36
Ratio of milk to water =36 ; (81-36) =36 : 45=4 : 5