Kunal purchased a notebook for Rs. 19.75, a pencil for Rs. 3.85 and a pen for Rs. 8.35 from a book shop. He gave a 50 rupee note to the shopkeeper. What amount will he get back?

Hint: We start solving the problem by finding the total cost incurred to Kunal for buying notebook, pencil and pen by adding individual costs of them. We then subtract this total cost from the Rs. 50 he just gave to the shopkeeper to find the amount that he gets back overall.

Complete step by step answer:
According to the problem, we are given that Kunal purchased a notebook of cost Rs. 19.75, a pencil of cost Rs. 3.85 and a pen of cost Rs. 8.35 from a book shop. We need to find the amount he gets back if he gives a 50 rupee note to the shopkeeper.
Let us first find the total cost incurred to Kunal by adding the costs of notebook, pencil and pen.
The total cost incurred to Kunal = $RS.\left( 19.75+3.85+8.35 \right)=Rs.31.95$.
So, the shopkeeper has to give the amount by cutting Rs. 31.95 from the Rs. 50.
Let us subtract Rs. 31.95 from Rs. 50 to get the amount that Kunal will get back.
The amount that Kunal will get back is $Rs.\left( 50-31.95 \right)=Rs.18.05$.
We have found that Kunal will get Rs. 18.05 back.

∴ The amount that Kunal will get back is Rs. 18.05.

Note: We should make sure to provide the answer accurately in paise by using the fact that one rupee contains 100 paise. We should check whether the final amount should be mentioned in round off value or normal before solving this problem. Whenever we get this type of problem, we first try to find the total cost incurred. Similarly, we can expect the problems to find the percentage of total amount left after buying a book, pen and pencil.