A pen is 4.5 yuan, which is 1.8 yuan more expensive than a notebook. How much is a pen and a notebook?
一支钢笔4.5元，比一本笔记本贵1.8元．一支钢笔和一本笔记本共多少元？
<gadget id="calculator">4.5 - 1.8</gadget>
<output>2.7</output>

<gadget id="calculator">2.7 + 4.5</gadget>
<output>7.2</output>

<result>7.2</result>