Lele spent 8.6 yuan to buy books, 3.2 yuan to buy pens, and paid 15 yuan to the salesperson. How much should I get back?
乐乐买书用去8.6元，买钢笔用去3.2元，付给售货员15元，应找回多少元？
<gadget id="calculator">8.6 + 3.2</gadget>
<output>11.8</output>

<gadget id="calculator">15 - 11.8</gadget>
<output>3.2</output>

<result>3.2</result>