A pen is 8 yuan, and a notebook is 2.5 yuan cheaper than a pen. How much does it cost to buy a notebook and a pen?
一支钢笔8元，一个笔记本比一支钢笔便宜2.5元，买一个笔记本和一支钢笔一共要多少钱？
<gadget id="calculator">8 - 2.5</gadget>
<output>5.5</output>

<gadget id="calculator">5.5 + 8</gadget>
<output>13.5</output>

<result>13.5</result>