$A$ sum of money put at simple interest trebles itself in $15$ years. The rate per cent per annum is (in $\%$):

The annual payment that will discharge a debt of ₹ $47250$ due in $3$ years at the rate of $5 \%$ simple interest per annum is:

$A$ sum of ₹ $8000$ is divided into two parts. The simple interest on the first part at the rate of $21 \%$ per annum is equal to the simple interest on the second part at the rate of $35 \%$ per annum. What is the interest (in ₹) of each part?

$A$ certain sum becomes ₹ $1020$ in $5$ years and ₹ $1200$ in $8$ years at simple interest. What is the value of Principal (in ₹)?

$A$ man invested $\frac{1}{3}$ of his capital at $7 \%$,$\frac{1}{4}$ at $8 \%$,and the remainder at $10 \%$. If the annual income is ₹ $561$,the capital (in ₹) is:

Shruti borrowed $Rs. 2500$ from her two friends. For one loan she paid $8 \%$ $p.a.$ and for the other $6 \%$ $p.a.$ simple interest. If she paid $Rs. 180$ as total interest for one year,how much did she borrow (in $Rs.$) at $8 \%$ $p.a.?$