Teacher Wang bought 5 tennis balls in the store, paid the salesperson 50 yuan, and got 5 yuan back. How much is each tennis ball on average?
王老师在商店里买了5个网球，付给营业员50元钱，找回了5元，平均每个网球多少钱？
<gadget id="calculator">50 - 5</gadget>
<output>45</output>

<gadget id="calculator">45 / 5</gadget>
<output>9</output>

<result>9</result>