240 yuan online shopping 5 packs of books, 4 books per pack, how much is the average per book?
240元网购5包书，每包4本，平均每本多少钱？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">240 / 20</gadget>
<output>12</output>

<result>12</result>