A and B can make a dam in 3 day's. B alone can make the dam in 6 day's. In how many days A alone can make the dam?

Question: A and B can make a dam in 3 day's. B alone can make the dam in 6 day's. In how many days A alone can make the dam?Solution:A's 1 day's work = ( 1/3 - 1/6 ) = 1/6∴ A alone can make the dam in 6 day's.