Teacher Wang bought 4 tubes of tennis balls for 120 yuan, each tube contains 5 balls, how much is each tennis ball?
王老师用120元钱买了4筒网球，每筒里面有5个，每个网球多少钱？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<result>6</result>