A ballpoint pen is 3.5 yuan, and an exercise book is 1.8 yuan cheaper than a ballpoint pen. How much does Xiao Ming pay for a ballpoint pen and an exercise book?
一枝圆珠笔3.5元，一本练习本比一枝圆珠笔便宜1.8元，小明买一枝圆珠笔和一本练习本共要多少钱？
<gadget id="calculator">3.5 - 1.8</gadget>
<output>1.7</output>

<gadget id="calculator">1.7 + 3.5</gadget>
<output>5.2</output>

<result>5.2</result>