One of the most important and conceptual question from linear equations in two variables in which we have been asked to find the no of coins a lady has if a lady has only 50-paisa coins and 25-paisa coins in her purse. If she has 50 coins in all totaling Rs.19.50.

RS Aggarwal, Class 10, chapter 3E, question no 3

Let x and y be the number of 50-paisa and 25-paisa coins respectively.

Then x + y = 50 ……….(i)

0.5x + 0.25y = 19.50 ………(ii) Multiplying (ii) by 2 and subtracting it from (i), we get

0.5y = 50 – 39

⇒ y = 11/0.5 = 22

Subtracting y = 22 in (i), we get

x + 22 = 50

⇒ x = 50 – 22 = 28

Hence, the number of 25-paisa and 50-paisa coins is 22 and 28 respectively