pen is 5.6 yuan, and a notebook is 8.7 yuan. Mr. Chen brought 20 yuan, how much money do you get back?
一支钢笔5.6元，一本笔记本8.7元．陈老师带了20元钱，找回多少钱？
<gadget id="calculator">5.6 + 8.7</gadget>
<output>14.3</output>

<gadget id="calculator">20 - 14.3</gadget>
<output>5.7</output>

<result>5.7</result>