A mining company owns two mines. These mines produce an ore that can be graded into two classes: regular grade and low grade. The company must produce at least tons of regular-grade and tons of low-grade ore per week. The first mine produces tons of regular-grade and tons of low-grade ore per hour. The second mine produces tons of regular-grade and tons of low-grade ore per hour. The operating cost of the first mine is per hour, and the operating cost of the second mine is