The problem asks for the profit percentage earned by a trader who mixes two types of rice and sells the mixture.

Determining Cost and Selling Price per kg

The trader mixes two varieties of rice:

• Variety 1: 255 kg at Rs. 170 per kg
• Variety 2: 265 kg at Rs. 170 per kg

Since both rice varieties have the same cost price (CP) of Rs. 170 per kg, the cost price of the mixture remains Rs. 170 per kg.

The selling price (SP) of the mixture is given as Rs. 204 per kg.

Calculating Profit per kg

The profit made on each kilogram of the mixture is the difference between the selling price and the cost price per kg.

Using LaTeX for the formula:

$\text{Profit per kg} = \text{SP per kg} - \text{CP per kg}$

Calculation:

$\text{Profit per kg} = \text{Rs. } 204 - \text{Rs. } 170 = \text{Rs. } 34$

Finding the Profit Percentage

The profit percentage is calculated based on the cost price.

Using LaTeX for the formula:

$\text{Profit \%} = \frac{\text{Profit per kg}}{\text{CP per kg}} \times 100$

Substituting the values:

$\text{Profit \%} = \frac{34}{170} \times 100$

Simplify the fraction:

$\frac{34}{170} = \frac{34 \div 34}{170 \div 34} = \frac{1}{5}$

Calculate the percentage:

$\text{Profit \%} = \frac{1}{5} \times 100 = 20\%$

The trader's profit percentage is 20%.