Two brothers and sisters go from home to school, the younger sister walks 45 meters per minute on foot, and the older brother rides a bicycle at 195 meters per minute. 20 minutes after the younger sister left, the elder brother left home by bicycle, and caught up with the younger sister a few minutes later?
兄妹两人由家到学校，妹妹步行每分钟走45米，哥哥骑车每分钟行195米．妹妹走20分钟后，哥哥骑车离家，几分钟后追上妹妹？
<gadget id="calculator">195 - 45</gadget>
<output>150</output>

<gadget id="calculator">20 / 150</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">45 * (2/15)</gadget>
<output>6</output>

<result>6</result>