A and B started a business with capitals of Rs. 12 lakhs and Rs. 24 lakhs respectively. A receives a monthly salary for running the business. At the end of the year they receive Rs. 1.80.000 each. What was the monthly salary of A (in Rs.)?

A’s capital : B’s capital = Rs. 12 lakhs : Rs. 24 lakhs = 1 : 2.
Hence after paying A’s fixed salary, the remaining profit must be shared in the ratio 1 : 2.

Let the monthly salary paid to A be $$x$$ rupees.
Salary for one year = $$12x$$ rupees.

Let the total profit of the firm before paying salary be $$P$$ rupees.
Amount left for distribution of profit after paying salary = $$P - 12x$$.

Share of A in this residual profit = $$\frac{1}{1+2}\,(P - 12x) = \frac{1}{3}\,(P - 12x)$$.
Share of B in this residual profit = $$\frac{2}{3}\,(P - 12x)$$.

According to the question, each partner finally receives Rs. 1,80,000.

For B (who gets no salary):
$$\frac{2}{3}\,(P - 12x) = 1,80,000$$
$$\Rightarrow P - 12x = 1,80,000 \times \frac{3}{2} = 2,70,000$$ $$-(1)$$

For A (who gets salary plus profit share):
$$12x + \frac{1}{3}\,(P - 12x) = 1,80,000$$ $$-(2)$$

Substitute the value of $$P - 12x$$ from $$(1)$$ into $$(2)$$:
$$12x + \frac{1}{3}\,(2,70,000) = 1,80,000$$
$$12x + 90,000 = 1,80,000$$
$$12x = 1,80,000 - 90,000 = 90,000$$
$$x = \frac{90,000}{12} = 7,500$$.

Therefore, A’s monthly salary is Rs. 7,500.

Option B which is: 7,500