Beibei bought a set of "Children's Encyclopedia" at Xinhua Bookstore, a total of 4 copies, paid 100 yuan, and got 28 yuan back. How much is each "Encyclopedia for Young People"?
贝贝在新华书店买了一套《少儿百科全书》，共4本，付了100元，找回28元．每本《少年百科全书》多少钱？
<gadget id="calculator">100 - 28</gadget>
<output>72</output>

<gadget id="calculator">72 / 4</gadget>
<output>18</output>

<result>18</result>