What annual payment will discharge a debt of  Rs.9760 due in 3 years at 25% per annum compound interest ?

Solution: Let the each installment be Rs ‘x’.  Then

$\begin{array}{l}\Rightarrow \frac{x}{(1+\frac{25}{100})}+\frac{x}{{(1+\frac{25}{100})}^2}+\frac{x}{{(1+\frac{25}{100})}^3}=9760\\ \Rightarrow \frac{x}{\left(\frac{5}{4}\right)}+\frac{x}{{\left(\frac{5}{4}\right)}^2}+\frac{x}{{\left(\frac{5}{4}\right)}^3}=9760\\ \Rightarrow \frac{4x}{5}+\frac{16x}{25}+\frac{64x}{125}=9760\\ \Rightarrow 100x+80x+64x=9760\times 125\\ x=\frac{9760\times 125}{244}\\ x=5000\end{array}$