A person X can do a piece of work worth 3000 in 6 days, but he engages an assistant Y and completes the work in 4 days. Find the share of the assistant Y in completing the work.

Y's part of the work is worth 1000.

X finishes work worth 3000 in 6 days, so X does 3000/6 = 500 per day.

In the 4 days taken, X does 4 x 500 = 2000.

The rest, 3000 - 2000 = 1000, is done by Y.

Payment follows work done, so Y gets 1000.