Amresh and Bhagwan together can do a piece of work in 20 days, Bhagwan and Chandar in 15 days, and  Chandar and Amresh in 30 days. In how many days can Amresh, Bhagwan, and Chandar working together complete the work?

Amresh and Bhagwan / अमरेश और भगवान = A + B = $\frac{1}{20}$
Bhagwan and Chandar / भगवान और चंदर = B + C =$\frac{1}{15}$
Chandar and Amresh / चंदर और अमरेश = C + A = $\frac{1}{30}$
Lcm = 60
=$ \frac{3}{60} + \frac{4}{60} + \frac{2}{60} = \frac{9}{60} $
2(A+B+C) के बराबर हैः
= 2(A+B+C) = $ \frac{9}{60}$
= A+ B + C =$ \frac{9}{120} = \frac{3}{40}$
= Total time =1/ (A + B + C)
Answer= $\frac{40}{3} = 13\frac {1}{3} $ days