Manish is four times as efficient as Puneet. Manish takes 90 days less than Puneet to complete a book. If both of them work together, then in how many days the book will be completed?

Ratio of times taken by Manish and Puneet = 1 : 4

The time difference is (4 - 1) 3 days while Puneet take 4 days and Manish takes 1 day.

If difference of time is 3 days, Puneet takes 4 days.

If difference of time is 90 days, Puneet takes = $$\frac{4}{3} \times 90 = 120$$ days

So, Manish takes 30 days

Manish's 1 day's work = $$\frac{1}{30}$$

Puneet's 1 day's work = $$\frac{1}{120}$$

(Manish + Puneet)'s 1 day's work together = $$\frac{1}{30} + \frac{1}{120} = \frac{5}{120} = \frac{1}{24}$$

$$\therefore$$ Manish and Puneet together can do the work in = 24 days

=> Ans - (C)