The distance from Xiao Ming's home to the school is 6 kilometers. In the past, it took him 20 minutes to get to the school by bus. Recently he began to ride a bicycle to school, known to travel 100 meters per minute less than riding a bus. How many minutes does it take Xiao Ming to ride a bicycle from home to school?
小明的家到学校的距离为6千米，过去他乘公共汽车用20分钟可到校．最近他开始骑自行车上学，已知骑自行车比乘公共汽车每分钟少行100米．问小明骑自行车从家到学校需多少分钟？
<gadget id="calculator">6 * 1_000</gadget>
<output>6_000</output>

<gadget id="calculator">6_000 / 20</gadget>
<output>300</output>

<gadget id="calculator">300 - 100</gadget>
<output>200</output>

<gadget id="calculator">6_000 / 200</gadget>
<output>30</output>

<result>30</result>