Interest on opening capitals: M = 4,00,000 times 6 percent = 24,000; R = 3,00,000 times 6 percent = 18,000. Total = 42,000.
Balance interest = 50,000 minus 42,000 = 8,000, on additional capital for 8 months.
Additional = 6%×88,000×12 = Rs. 2,00,000.