Question

A total of $324$ coins of $20$ paise and $25$ paise make a sum of Rs. $71$. The number of $25$-paise coins is

• A. $120$
• B. $124$
• C. $144$
• D. $200$

Answer 1

The correct option is B $124$

Let the number of $20$-paise coins be $x$. Then, number of $25$-paise coins $=(324-x)$.
Therefore $0.20\times x+0.25(324-x)=71\iff 20x+25(324-x)=7100$
$\iff 5x=1000\iff x=200$. Hence, number of $25$-paise coins $=(324-x)=124$.