1. **Stating the problem:** A shopkeeper marks a shirt at 1200. We need to understand what this means and possibly find related values like cost price, selling price, or discount if more information is given. 2. **Explanation:** The marked price (MP) is the price at which the shopkeeper labels the product before any discount. 3. **Important formulas:** - Selling Price (SP) = Marked Price (MP) - Discount - Profit or Loss = SP - Cost Price (CP) 4. **Since only the marked price is given (1200), without additional information such as cost price or discount, we cannot calculate further values.** 5. **Summary:** The shirt is marked at 1200, which means the shopkeeper intends to sell it at this price before any discount. **Final answer:** The marked price of the shirt is $1200$.