The market value of a 10.5% stock, in which an income of Rs. 756 is derived by investing Rs. 9000, brokerage being %, is

For an income of Rs. 756, investment = Rs. 9000.
For an income of Rs. $\frac{21}{2}$ , investment = $Rs. \left(\frac{9000}{756} \times \frac{21}{2}\right) = Rs. 125.$
$\therefore$ For a Rs. 100 stock, investment = Rs. 125.
Market value of Rs. 100 stock = $Rs. \left(125 - \frac{1}{4}\right) = Rs. 124.75$