Question

arvind can do a piece of work in 20 days, bhanu in 30 days and chetan in 60 days. all begin to do it together, but arvind leaves after 6 days and bhanu leaves 6 days before the completion of the work. how many days did the work last?​

Answer 1

Arvind can do a piece of work in 20 days; or, he does 1/20th of the work in a day. Similarly, bhanu does 1/30th of the work per day, and Chetan does 1/60th. After 6 days, they have done 6/20+6/30+6/60, or 3/5ths of the work, leaving 2/5ths to be done. Now, let n be the amount of days Chetan kept working, and n-6 be the amount of time Bhanu kept working. Then:

n/60 + n-6/30=2/5

n+2(n-6)=24

3n=36

n=12

A worked 6 days, B worked 12 days, and C worked 18 days