Ajit is two times as good a workman as Badrinath and therefore is able to finish a job in 30 days less than Badrinath. Working together, they can do it in

Ratio of times taken by Ajit and Badrinath = 1 : 2

The time difference is (2 - 1) 1 day while Badrinath take 2 days and Ajit takes 1 day.

If difference of time is 1 days, Badrinath takes 2 days.

If difference of time is 30 days, Badrinath takes = $$\frac{2}{1} \times 30 = 60$$ days

So, Ajit takes 30 days

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

Badrinath's 1 day's work = $$\frac{1}{60}$$

(Ajit + Badrinath)'s 1 day's work together = $$\frac{1}{30} + \frac{1}{60} = \frac{3}{60} = \frac{1}{20}$$

$$\therefore$$ Ajit and Badrinath together can do the work in = 20 days

=> Ans - (D)