Lele spent 8.55 yuan to buy books, 3.8 yuan to buy pens, and 30 yuan to the salesperson. How much should I get back?
乐乐买书用去8.55元，买钢笔用去3.8元，付给售货员30元，应找回多少元？
<gadget id="calculator">8.55 + 3.8</gadget>
<output>12.35</output>

<gadget id="calculator">30 - 12.35</gadget>
<output>17.65</output>

<result>17.65</result>