1. **Problem Statement:** A trader mixes 26 kg of rice costing 20 per kg with 30 kg of rice costing 36 per kg. He sells the mixture at 30 per kg. We need to find his profit percentage. 2. **Formula for Profit Percentage:** $$\text{Profit Percentage} = \left(\frac{\text{Selling Price} - \text{Cost Price}}{\text{Cost Price}}\right) \times 100$$ 3. **Calculate Cost Price (CP) of the mixture:** $$\text{CP} = (26 \times 20) + (30 \times 36) = 520 + 1080 = 1600$$ 4. **Calculate Selling Price (SP) of the mixture:** Total weight = $26 + 30 = 56$ kg $$\text{SP} = 56 \times 30 = 1680$$ 5. **Calculate Profit:** $$\text{Profit} = \text{SP} - \text{CP} = 1680 - 1600 = 80$$ 6. **Calculate Profit Percentage:** $$\text{Profit Percentage} = \left(\frac{80}{1600}\right) \times 100 = 5\%$$ **Answer:** The trader makes a profit of 5%.