Xiaohua had walked 200 meters from home, and her sister rode a bicycle from home to chase Xiaohua. It is known that Xiaohua walks 70 meters per minute, and her sister rides a bicycle at 120 meters per minute. How many minutes does it take for my sister to catch up with Xiaohua?
小华从家里已走出200米，她的姐姐从家里骑自行车去追小华．已知小华每分钟走70米，姐姐骑自行车每分钟行120米．姐姐追上小华需要多少分钟？
<gadget id="calculator">120 - 70</gadget>
<output>50</output>

<gadget id="calculator">200 / 50</gadget>
<output>4</output>

<result>4</result>