Xiaofang bought 4 copies of "Golden Childhood", paid 50 yuan, and got 7.2 yuan back. How much is the price of each book?
小芳买了4本《金色童年》，付出50元，找回7.2元．每本书售价是多少元？
<gadget id="calculator">50 - 7.2</gadget>
<output>42.8</output>

<gadget id="calculator">42.8 / 4</gadget>
<output>10.7</output>

<result>10.7</result>