The school bought 5 boxes of volleyballs, each with 4 volleyballs, and the total cost was 400 yuan. How much is each volleyball?
学校买来5箱排球，每箱4只，一共用了400元，每只排球多少元？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">400 / 20</gadget>
<output>20</output>

<result>20</result>