Ajay, Vijay and Sashi can do a piece of work in 20, 40 and 60 days, respectively. In how many days can Ajay do the work if he is assisted by Vijay and Sashi on every fourth day?

$\frac{50}{3}$ days

Ajay = 20 days, Vijay = 40 days, Sashi = 60 days,

⇒ Ajay started the work and was assisted by Vijay and Sashi on every 4th day,therefore

1st day = 6 units

2nd day = 6 units

3rd day = 6 units,

4th day = 6 + 3 + 2 = 11 units,

Every 4 days = 29 units,

So in 16 days, 116 units of work will be completed.

Therefore in \( {16 }_{ 6}^{4 } \) = \( {16 }_{ 3}^{2 } \) = \(\frac{50}{3}\) days.