Incomes of x and y are in the ratio 4 : 3. Their expenditure are in the ratio 12 : 7. Both save Rs. 3200 at the end of the month, then the income of x is = ?

Answer: Option B

Let their income be 4x and 3x
Their savings = Rs. 3200 each
According to the question,
$$\begin{array}{rl}& \Rightarrow \frac{4x-3200}{3x-3200}=\frac{12}{7}\\ & \Rightarrow \frac{x-800}{3x-3200}=\frac{3}{7}\\ & \Rightarrow 7x-5600=9x-9600\\ & \Rightarrow 2x=4000\\ & \Rightarrow x=2000\\ & \Rightarrow \text{A}=2000\\ & \Rightarrow \text{Income of A}=4x\\ & \Rightarrow 4\times 2000=\text{Rs}\text{. }8000\end{array}$$