DRDO Multi tasking staff Model paper 9

Let B takes “n” days to complete work individually. So, A takes (n - 40) days.
For same work, Since A is 6 times faster than B takes 6 times more days that A does take.
So we have,
⇒ n = 6(n-40)
⇒ n = 48 days for B.
∴ For A = n-40 = 8 days.