For what sum (in ₹) will the simple interest at $R \%$ per annum for $2$ years be $R$?

Sumit lends ₹ $10000$ for $2$ $years$ at $20 \%$ per annum simple interest. After $1$ $year,$ he receives ₹ $6000$. How much (in ₹) will he receive next year?

$A$ sum of money at simple interest becomes four times in $24$ years. The rate per cent of interest per annum is

Rashmi lent $Rs. 600$ to Geeta for $2 \,yr$ and $Rs. 150$ to Seeta for $4 \,yr$ at the same rate of interest and received altogether $Rs. 80$ as simple interest from both. Find the rate of interest (in $\%$).

An automobile financier claims to be lending money at simple interest,but he includes the interest every six months for calculating the principal. If he is charging an interest of $10 \%$ per annum,the effective rate of interest becomes (in $\%$):

$A$ sum of money becomes $\frac{8}{5}$ of itself in $5$ $years$ at a certain rate of interest. The rate per cent per annum is