Guo Haiyan bought 3 copies of "Science Talk", paid 50 yuan, and got 8 yuan back. How much is each book?
郭海燕同学买了3本《科学趣谈》，付了50元，找回8元．每本多少元？
<gadget id="calculator">50 - 8</gadget>
<output>42</output>

<gadget id="calculator">42 / 3</gadget>
<output>14</output>

<result>14</result>