A truck pulls 100 trucks of goods every month, but this month it only pulls 2 trucks a day. How many trucks are left? (30 days a month)
一辆货车每个月拉100车货物，可这个月它每天只拉了2车，还有几车没拉？(一个月30天)
<gadget id="calculator">2 * 30</gadget>
<output>60</output>

<gadget id="calculator">100 - 60</gadget>
<output>40</output>

<result>40</result>