C and D together can make a chair in 4 days and C alone can make this chair in 12 days. In how many days D alone can make this chair?

10 days 6 days 4 days 8 days

6 days

C + D = 4 days, C = 12 days, ⇒ C + D = 3,   (Efficiency) ⇒ 1 + D = 3, ⇒ D = 2, Time required by D to complete total work alone = \(\frac{12}{2}\) = 6 days,  ..(\(\frac{Work}{Efficiency}\) = Time)