The monthly incomes of A and B are in the ratio 4:5, their expenses are in the ratio 5 : 6. If 'A' saves Rs.25 per month and 'B' saves Rs.50 per month, what are their respective incomes? A) Rs.400 and Rs.500 B) Rs.240 and Rs.300 C) Rs.320 and Rs.400 D) Rs.440 and Rs.550 E) NONE