P started a business in 1990 by investing Rs.25,000. She invested Rs. 10,000 as additional amount in 1991 and her friend Q joined her with an amount of Rs.35,000. P invested another Rs. 10,000 in 1992 and R joined them with Rs. 35,000. At the end of these 3 years, they earned a profit of Rs. 150,000. Find Q's share? a) Rs.50,000 b) Rs.65,000 c) Rs.75,000 d) Rs.15,000