Question

A and b together can complete a work in 15 days. B and c together can complete the same task in 20 days. A and c together can complete the task in 30 days. What is the respective ratio of the number of days taken by a while completing this task alone to the number of days taken lecture-21 time and work-i ( -i) by c while completing this task alone

Answer 1

One day work of a and b, b and c, c and a = 1/15,1/20,1/30
One day work of a,b,c working together = (1/15 + 1/20 + 1/30)/2 (BECAUSE ALL A,B,C OCCUR TWO TIMES)
One day work of a,b,c working together =(9/60)/2
One day work of a,b,c working together =9/120=3/40
Number of days needed to complete the work = 1/one days work
=40/3
Number of days needed by a to complete the work alone = the work completed in one day together - the work completed by b and c in one day
A one day work = 3/40 - 1/20
= 1/40
A can complete the work in 40 days

And now u can find the ratio

Hope this helps you