A pen is 38.5 yuan, a schoolbag is 19.6 yuan more expensive than a pen, a schoolbag is 20.3 yuan more than a pencil case, which one is more expensive, a pen or a pencil case? How much is it expensive?
一枝钢笔38.5元，一个书包比钢笔贵19.6元，书包比一只笔盒多20.3元，一枝钢笔和一只笔盒哪个贵？贵多少元？
<gadget id="calculator">19.6 - 20.3</gadget>
<output>-0.7</output>

<gadget id="calculator">38.5 + (-0.7)</gadget>
<output>37.8</output>

<gadget id="calculator">38.5 - 37.8</gadget>
<output>0.7</output>

<result>0.7</result>