On Sunday morning, my elder brother and younger brother went to practice running. The elder brother ran 110 meters per minute, and the younger brother ran 80 meters per minute. The younger brother ran half an hour longer than the elder brother, and the result was 900 meters more than the elder brother. So, how many meters did the elder brother run?
星期天早晨，哥哥和弟弟去练习跑步，哥哥每分钟跑110米，弟弟每分钟跑80米，弟弟比哥哥多跑了半小时，结果比哥哥多跑了900米，那么，哥哥跑了多少米．
<gadget id="calculator">30 * 80</gadget>
<output>2_400</output>

<gadget id="calculator">2_400 - 900</gadget>
<output>1_500</output>

<gadget id="calculator">110 - 80</gadget>
<output>30</output>

<gadget id="calculator">1_500 / 30</gadget>
<output>50</output>

<gadget id="calculator">110 * 50</gadget>
<output>5_500</output>

<result>5_500</result>