Question

A lady has only 25-paisa and 50-paisa coins in her purse. If she has 50 coins in all
totalling ₹19.50, how many coins of each kind does she have?

Answer 1

Let the x and y be the number of 50-paisa and 25-paisa conis respectively. Then
$$\begin{gathered} x+y=50.....\left(i\right) \\ 0.5x+0.25y=19.50.....\left(ii\right) \end{gathered}$$
Multiplying (ii) by 2 and subtracting it from (i), we get
$$\begin{gathered} 0.5y=50-39 \\ \Rightarrow y=\frac{11}{0.5}=22 \end{gathered}$$
Subtracting y = 22 in (i), we get
$$\begin{gathered} x+22=50 \\ \Rightarrow x=50-22=28 \end{gathered}$$
Hence, the number of 25-paisa and 50-paisa conis are 22 and 28 respectively.