Interest is $30\%$ in $90-91$ which is $= 30\% \times 130$ lakh
$= 39\hspace{0.1cm} lakh$
Interest is $40\%$ in $91-92$ which si $= 40\% \times 160$ lakh
$= 64 \hspace{0.1cm}lakh$
∴ Total interest given in $2$ years $(90-91$ & $91-92)$ = $(39+64)$ lakh = $103 \hspace{0.1cm} lakh$
On an average, $20\%$ rate of interest was charged on borrowed funds
$∴ \hspace{0.1cm} 20\% \text{ of borrowed fund = 103 lakh}$
$\text{∴ Total amount of borrowed fund in 90-91 & 91-92 =} $ $\dfrac{100}{20} \times 103$ lakh
$ \color{green}{= 515\hspace{0.1cm} lakh}$