1. **Problem statement:** A manufacturer sells an item to a wholesaler with an 18% profit. The wholesaler sells it to a retailer with a 20% profit. The retailer sells the item to a customer for Rs.20355 with a 25% profit. Find the manufacturer's cost price. 2. Let the manufacturer's cost price be $x$. 3. Manufacturer's selling price to wholesaler = $x + 0.18x = 1.18x$ 4. Wholesaler sells to retailer at 20% profit, so wholesaler's selling price = $1.18x + 0.20(1.18x) = 1.18x \times 1.20 = 1.416x$ 5. Retailer sells to customer at 25% profit, so selling price = $1.416x + 0.25(1.416x) = 1.416x \times 1.25 = 1.77x$ 6. Given retailer's selling price is Rs.20355, so $$1.77x = 20355$$ 7. Solve for $x$: $$x = \frac{20355}{1.77} = 11500$$ **Final answer:** The cost price of the manufacturer is Rs.11500.