What will be the ratio of simple interest earned by a certain amount at the same rate of interest for $6$ years and that of $9$ years?

Dalajit lent ₹ $10800$ to Jaabir for $3$ $years$ and ₹ $7500$ to Kabir for $2$ $years$ on simple interest and received ₹ $1422$ in all from both of them as interest. The rate of interest (in $\%$) per annum is

Arun gives his wife Asha a birthday gift,giving her each year a number of rupees equal to the number of years of her age. If her birthday falls on $August \, 8$,what sum must be placed at simple interest at $7 \%$ on $January \, 1$,before she is $42$,in order to raise the required sum (in $Rs.$)?

$A$ certain amount earns simple interest of ₹ $1,750$ after $7$ years. Had the interest rate been $2 \%$ more per annum,how much more interest would it have earned (in ₹)?

Income of Hemant was Rs. $4000$. In the first $2$ years,his income decreased by $10\%$ and $5\%$ respectively,but in the third year,the income increased by $15\%$. What was his income (in Rs.) at the end of the third year?

$A$ man invested $\frac{1}{3}$ of his capital at $7 \%$,$\frac{1}{4}$ at $8 \%$,and the remaining at $10 \%$ rate of simple interest. If his annual income from interests is ₹ $561$,then the total capital invested (in ₹) was: