Question

A can do job 6days and a&b can do it together in 2 days.how many days will be taken by b to do the job alone

Answer 1

A can do work in 6 days then
A's one day work will be 1/6
Since  A and  B can do a job in  2 days,
Then

$\frac{1}{ a} + \frac{1}{b} = \frac{1 }{2}$
But A can finish the work in 6  days.
$\frac{1}{a} = \frac{1}{6}$
So
$\frac{1}{b} + \frac{1}{6} = \frac{1}{2}$
Thus b=3