A and B start a business investing Rs. 10000 and Rs. 6000 respectively. After 3 months, A takes out Rs. 2000 from his investment and B adds Rs. 4000 in his investment. After another 3 months, C enters into the business investing Rs. 15000. If they earn a profit of Rs. 31500 after 1 year, then find the share of B in this profit?