Hufflepuff Industries produces badger sweaters and currently uses \[20\] units of labor and \[30\] units of capital. The marginal product of the \[20th\] unit of labor is \[100\] sweaters, and the marginal product of the \[30th\] unit of capital is \[200\] sweaters. If the cost of each unit of labor \[(w)\] is \[\$20\] and this firm minimizes costs, what is the rental rate of capital \[(r)\]