Question

A b and c can do a piece of work in 10 20 30 days respectively they started working together but a and b left the work 5 and 4 days before the work was completed then time taken to complete

Answer 1

A, B and C can do the work in 12, 15 & 20 days respectively. They are essentially doing the same work, regardless of what the work is actually. Let the amount of work they do, in total, be x. This will be equal for all of them. For calculation, assume this to be the LCM of all, so that we don't have to deal with fractions.

Now, LCM of 12, 15 & 20 is 60. Dividing 60 by respective days will give us efficiency of A,B & C. Which is