An oil company requires 12,000, 20,000 and 15,000 barrels of high-grade, medium grade and low grade oil, respectively. Refinery A produces 100, 300 and 200 barrels per day of high grade, medium grade and low grade, respectively, while refinery B produces 200,400 and 100 barrels per day of high-grade, medium grade and low grade, respectively. If refinery A costs Rs 400 per day and refinery B costs Rs 300 per day to operate, how many days should each be run to minimize costs while satisfying requirements.