Brother and sister go to school together, the speed of brother is 85 meters per minute, the speed of sister is 50 meters per minute, they start at the same time. When the elder brother arrived at the school, he found that he did not bring the math books with him, so he went back home to get them, and met his younger sister 210 meters away from the school. How far is home from school?
哥哥和妹妹一起去学校，哥哥的速度是每分钟85米，妹妹的速度是每分钟50米，他们同时出发．哥哥到达学校后发现数学书没带，又返回家去拿，在离学校210米处和妹妹相遇．家离学校有多远？
<gadget id="calculator">85 - 50</gadget>
<output>35</output>

<gadget id="calculator">2 / 35</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">210 * (2/35)</gadget>
<output>12</output>

<gadget id="calculator">50 * 12</gadget>
<output>600</output>

<gadget id="calculator">600 + 210</gadget>
<output>810</output>

<result>810</result>