The two brothers and sisters went to school from A at the same time. The elder brother walked 90 meters per minute, and the younger sister walked 60 meters per minute. After 3 minutes, the elder brother realized that he had forgotten his textbooks, so he immediately returned home by the same route. After taking the textbooks, he rushed to school immediately. I caught up with my sister 100 meters away from the school. How many meters is their home from the school?
兄妹两人同时从甲去学校，哥哥每分钟走90米，妹妹每分钟走60米，3分钟后，哥哥发现忘带了课本，立即原路返回家中，取了课本后立即赶往学校，正好在离学校100米处追上妹妹．他们家离学校有多少米？
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<gadget id="calculator">6 / 30</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">60 * (1/5)</gadget>
<output>12</output>

<gadget id="calculator">60 * 12</gadget>
<output>720</output>

<gadget id="calculator">720 + 100</gadget>
<output>820</output>

<result>820</result>