There are two roads from the east of the city to the west of the city. A car travels at the same speed of 600 m/min. It takes 21 minutes to walk the first road and 19 minutes to walk the second road. How much longer is the first road than the second?
从城东到城西之间有两条路，一辆汽车以600米/分钟的同样速度行驶，走第一条路需要21分钟，走第二条路需要19分钟．第一条路比第二条长多少米？
<gadget id="calculator">21 - 19</gadget>
<output>2</output>

<gadget id="calculator">2 * 600</gadget>
<output>1_200</output>

<result>1_200</result>