From point A to point B, travel 60 kilometers per hour and arrive on time, actually travel 20 kilometers per hour, and arrive 0.5 hours earlier. How many kilometers are there between places A and B?
从甲地到乙地，每小时行60千米，能准时到达，实际每小时多行20千米，结果提前0.5小时到达，甲、乙两地相距多少千米？
<gadget id="calculator">60 * 0.5</gadget>
<output>30</output>

<gadget id="calculator">20 * 0.5</gadget>
<output>10</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">20 - 60</gadget>
<output>-40</output>

<gadget id="calculator">60 + (-40)</gadget>
<output>20</output>

<gadget id="calculator">40 / 20</gadget>
<output>2</output>

<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<result>120</result>