1. **Problem Statement:** A man buys a cow for 3000 and sells it for 3600 on credit for 2 years with a simple interest rate of 10% per annum. We need to find if he made a gain or loss and calculate the amount. 2. **Formula for Simple Interest:** $$SI = \frac{P \times R \times T}{100}$$ where $P$ is principal, $R$ is rate per annum, and $T$ is time in years. 3. **Calculate the interest on 3600 for 2 years:** $$SI = \frac{3600 \times 10 \times 2}{100} = \frac{72000}{100} = 720$$ 4. **Total amount received by the seller after 2 years:** $$3600 + 720 = 4320$$ 5. **Compare the total amount received with the cost price:** Cost price = 3000 Total received = 4320 6. **Calculate gain:** $$Gain = 4320 - 3000 = 1320$$ 7. **Conclusion:** The man made a gain of 1320.