Let the monthly incomes of A and B be 13x and 7x respectively.

Let the expenditure of A and B be 9y and 7y respectively.

It is given that the saving of A and B are Rs 8000 each

∴ 13x – 9y = 8000 (1)

7x – 7y = 8000 (2)

Saving these two equations, you will obtain

y = -12000/7 and x = -4000/7

Since x and y are negative values so, the expenditure and incomes of A and B are negative values which is not possible