A company makes 3 models of calculators: A, B, and C at factory I and factory II. The company has orders for at least 6400 calculators for model A, 4000 calculators for model B, and 4800 calculators for model C. At factory I, 50 calculators of model A, 50 of model B, and 30 of model C are made every day; at factory II, 40 calculators of model A, 20 of model B, and 40 of model C are made every day. It costs Rs 12000 and Rs 15000 each day to operate factory I and II, respectively. Find the number of days each factory should operate to minimise the operating costs and still meet the demand.
