A sum of Rs. 6.25 is made up of 80 coins which are either 10 paise or 5 paise coins. How many coins are there of 10 paise?

$\begin{array}{l}RS=1\Rightarrow 100paise\\ RS6.25=625paise\end{array}$

$x=10$ paise coins

$y=5$ paise coins

$x+y=80\_\_\_\_\_\_\left(1\right)$

Total value of coins $Rs6.25=625$ paise

$10x+5y=625\_\_\_\_\_\_\left(2\right)$

$\therefore$ by solving two equations.

$x=45\Rightarrow$no. of 10 paise coins

$y=35\Rightarrow$no. of 5 paise coins