Explanation

First, calculate the total cost of the books:

3 books x Rs 16 = Rs 48

4 books x Rs 23 = Rs 92

Total cost = Rs 48 + Rs 92 = Rs 140

Next, calculate the total number of books: 3 + 4 = 7 books

Now, divide the total cost by the total number of books to find the average price: Rs 140 ÷ 7 = Rs 20

The correct answer is: 20.