Wang Ning bought two books, one priced at 7.25 yuan and the other at 6.85 yuan. He paid 20 yuan, how much should he get back?
王宁买了两本书，一本价格是7.25元，另一本是6.85元，他付出20元，应找回多少元？
<gadget id="calculator">20 - 7.25 - 6.85</gadget>
<output>5.9</output>

<result>5.9</result>