An office manager buys pens and notebooks. The price of each pen is the same, and the price of each notebook is the same. A purchase of 10 pens and 5 notebooks costs $25. A second purchase of 6 pens and 8 notebooks costs $30. Let $p$ be the price, in dollars, of each pen and $n$ be the price, in dollars, of each notebook. Which system of linear equations represents this situation?