The two brothers and sisters went to school from home at the same time. The elder brother walked 90 meters per minute, and the younger sister walked 60 meters per minute. When they arrived at the school gate, the elder brother found that he had forgotten his textbooks. He immediately returned home to pick up the books and walked 180 meters away from the school. Met with my sister, how many meters is their home from the school?
兄妹两人同时从家出发上学校，哥哥每分钟行90米，妹妹每分钟行60米，到校门口时哥哥发现忘带课本，立即由原路返家取书，行到离学校180米处与妹妹相遇，他们的家离学校有多少米？
<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<gadget id="calculator">2 / 30</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">180 * (1/15)</gadget>
<output>12</output>

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

<gadget id="calculator">720 + 180</gadget>
<output>900</output>

<result>900</result>