Explanation
The bookseller sold the book for Rs.60 to make a profit of 20%. This means that the selling price (Rs.60) is 120% of the cost price (100% + 20% profit).
To find the cost price, we can set up an equation:
Selling Price = Cost Price + Profit
60 = Cost Price + (20% of Cost Price)
Let's convert the percentage to a decimal and simplify:
60 = Cost Price + 0.20(Cost Price)
60 = 1.20(Cost Price)
Now, divide both sides by 1.20:
Cost Price = 60 / 1.20
Cost Price = 50
So, the cost price of the book is Rs.50.
To earn a profit of 10%, the bookseller should have sold the book for:
Selling Price = Cost Price + Profit
= 50 + (10% of 50)
= 50 + 5
= 55
Therefore, the correct answer is: 55