The price of a math book is Tk. 500, but you have only Tk. 350 with you. If you get a discount of 20%, how much money do you need to borrow from a friend so that you can buy the book?

Question: The price of a math book is Tk. 500, but you have only Tk. 350 with you. If you get a discount of 20%, how much money do you need to borrow from a friend so that you can buy the book?

Solution:
In 20% discount,
Original price 100 taka then discount price 80 taka
Original price 1 taka then discount price 80/100 taka
Original price 500 Taka then discount price (80 × 500)/100 Taka
= 400 taka

I need to borrow = (400 - 350) Taka
= 50 taka