Question

A And b can do a piece of work in 8 days if a takes 24 days then how many days dose b take alone

Answer 1

A and B together take to complete the work in 8 days.
A and B's alone 1 day work = 1/8
A completes the work in 24 days.
A's alone 1 day work = 1/24
Therefore, B's alone 1 day work = 1/8 - 1/24 = 2/24 = 24/2 = 12 days.
Required answer = 12 days.

Answer 2

one's day work for of A and B=1/A+1/B=1/8
one's day work for A =1/A=1/24
1/24+1/B=1/8
1/B=1/8-1/24
1/B=16/8*24=1/12
B will takes 12 days