A, B and C invested in a business and their investments are in the ratio 2 : 3 : 4. If A gets 20% of the total profit as salary and rest is divided according to investment , then find the share of A, if B gets Rs. 3600.

The total profit is denoted by \(x\). The share of B, which is 80% of \(\frac{3}{9}\) of \(x\), is Rs. 3600. Therefore, we can set up the equation:

\[ \frac{4}{5} \times \frac{3}{9} \times x = 3600 \]

Solving for \(x\):
\[ x = \frac{3600 \times 5}{4} \times \frac{9}{3} \]
\[ x = 13500 \]

Now, A’s share is 20% of the total profit as salary plus 80% of his investment share of the profit. Therefore, A’s share is:

\[ \text{A’s share} = \frac{1}{5} \times 13500 + \frac{4}{5} \times \frac{2}{9} \times 13500 \]
\[ \text{A’s share} = 2700 + 2400 \]
\[ \text{A’s share} = 5100 \]

So, the share of A is Rs. 5100.