1. The manager of a hardware store sells batteries for \( \$ 5 \) a package. She wants to see how much money she will earn if she increases the price in \( 10 c \) increments. A model of the price change is the revenue function \( R ( x ) = - x ^ { 2 } + 10 x + 3000 \) , where \( x \) is the number of \( 10 \varphi \) increments and \( R ( x ) \) is in dollars. Explain how to determine the maximum revenue.
2. Determine the maximum revenue generated by the manager in question \( 1 \) .