The total cost price of 8 pens and 12 bottles together is Rs. 440. Find at what price 10 pens and 15 bottles should be sell to receive a profit of 20%.

To find the selling price of 10 pens and 15 bottles in order to make a profit of 20%, we need to follow these steps:

Step 1: Calculate the cost price of 1 pen and 1 bottle. To find the cost price of 1 pen, we divide the total cost price of 8 pens and 12 bottles by the total number of pens, which is 8. Cost price of 1 pen = Rs. 440 / 8 = Rs. 55

Similarly, to find the cost price of 1 bottle, we divide the total cost price by the total number of bottles, which is 12. Cost price of 1 bottle = Rs. 440 / 12 = Rs. 36.67 (rounded to two decimal places)

Step 2: Calculate the total cost price of 10 pens and 15 bottles. To find the total cost price of 10 pens, we multiply the cost price of 1 pen by 10. Total cost price of 10 pens = Rs. 55 * 10 = Rs. 550

To find the total cost price of 15 bottles, we multiply the cost price of 1 bottle by 15. Total cost price of 15 bottles = Rs. 36.67 * 15 = Rs. 550.05 (rounded to two decimal places)

Step 3: Calculate the profit amount. To calculate the profit amount, we multiply the total cost price by the profit percentage and divide it by 100. Profit amount = (Total cost price * Profit percentage) / 100 Profit amount = (Rs. 550 + Rs. 550.05) * 20 / 100 = Rs. 220.01 (rounded to two decimal places)

Step 4: Calculate the selling price. To find the selling price, we add the profit amount to the total cost price. Selling price = Total cost price + Profit amount Selling price = Rs. 550 + Rs. 220.01 = Rs. 770.01 (rounded to two decimal places)

Therefore, to make a profit of 20%, the selling price of 10 pens and 15 bottles should be Rs. 770.01.