Step 1: Identify the concept.
This is an example of **profit earning** through sales. The concept used here is **unit profit** which is calculated by dividing the total profit by the number of items sold.
Step 2: Calculation of profit per chair.
The total earnings from selling 15 chairs = ₹ 3000
Profit per chair = \frac{\text{Total Earnings}}{\text{Number of chairs}} = \frac{3000}{15} = ₹ 200.
Step 3: Conclude.
Therefore, Abhijeet earned a profit of ₹ 200 for each chair sold.
Final Answer: \[ \boxed{Profit \; earned \; per \; chair \; = ₹ 200} \]