A manufacturing company has two plants, each capable of producing smartphones, tablets, and Bluetooth headphones. The daily production capacities of each plant are as follows.
Plant I Plant II
Smartphones........................1000.....................2000
Tablets...............................3000.....................2000
Bluetooth headphones............2000......................1000
Plant I costs $15,000 per day to operate, whereas plant II costs $12,000. How many days should each plant be operated to fill an order for 100,000 smartphones, 180,000 tablets, and 100,000 Bluetooth headphones at the minimum cost?