Two brothers go to school, the younger brother walks first, and after 16 minutes away from home, the elder brother chases him by bicycle, the speed is three times that of the younger brother, how many minutes does it take for the older brother to catch up with the younger brother?
哥弟俩上学，弟弟先步行，离家16分钟后哥哥骑车追他，速度是弟弟的3倍，哥哥追上弟弟需多少分钟．
<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">1 * 8</gadget>
<output>8</output>

<result>8</result>