At 9 o'clock in the morning, Xiaoyu and his younger brother set off from home to participate in activities at school at the same time. Xiaoyu rode a bicycle and walked 300 meters per minute; his younger brother walked 70 meters per minute. After Xiaoyu arrived at the school, he stayed for half an hour and then returned home. It was 10:10 when he met his younger brother who was going to school. Do you know how many meters are there from home to school?
上午9时，小宇和弟弟同时从家出发去学校参加活动，小宇骑自行车，每分钟行300米；弟弟步行，每分钟行70米．小宇到达学校后，呆了半个小时产即返回家中，途中遇到正前往学校的弟弟时是10时10分．你知道从家到学校有多少米吗？
<gadget id="calculator">70 - 30</gadget>
<output>40</output>

<gadget id="calculator">300 * 40</gadget>
<output>12_000</output>

<gadget id="calculator">70 * 70</gadget>
<output>4_900</output>

<gadget id="calculator">12_000 + 4_900</gadget>
<output>16_900</output>

<gadget id="calculator">16_900 / 2</gadget>
<output>8_450</output>

<result>8_450</result>