Let the annual incomes of the two persons be ₹ 9x and ₹ 7x,respectively. Also, the expenses of the two persons be ₹ 4y and ₹3y, respectively ∴9x−4y=2000....(1) 7x−3y=2000..(2) Solving (1) and (2), we get x=2000 and y=4000 ∴ Difference in their annual incomes =9x–7x =2x=₹4,000