A comic book is 3.6 yuan, a story book is 4.2 yuan. Xiao Ming bought one copy each and paid 10 yuan. How much should I get back?
一本漫画书3.6元，一本故事书4.2元．小明各买了一本，付了10元，应找回多少元？
<gadget id="calculator">3.6 + 4.2</gadget>
<output>7.8</output>

<gadget id="calculator">10 - 7.8</gadget>
<output>2.2</output>

<result>2.2</result>