Rohit and Usha can complete a task individually in 24 days

Solution

Let the total work be 120 units (LCM of 24 and 60)

Efficiency of Rohit = (120/24) = 5 units/day

Efficiency of Usha = (120/60) = 2 units/day

Let the efficiency of Vipul be 'm' units/day.

So, 5 X (240/19) + 2 X (240/19) + m X (240/19) = 120

Or, (1200/19) + (480/19) + (240m/19) = 120

Or, (1680/19) + (240m/19) = 120

Or, (240m/19) = 120 - (1680/19) = (600/19)

Or, 240m = 600

Or, 'm' = 2.5

Ratio of the wages of Rohit, Usha and Vipul respectively = 5:2:(2.5) = 10:4:5

Therefore, wages earned by Vipul = (5/19) X 10,260 = Rs. 2,700