My elder brother rides a bicycle, and Xiao Ming walks from home to the park at the same time. When my elder brother arrives at the park 10 minutes later, Xiao Ming is still 1200 meters away from the park. It is known that the speed of my brother riding a bicycle is three times that of Xiao Ming's walking speed. How many meters does Xiao Ming walk per minute?
哥哥骑自行车，小明步行同时从家出发去公园，10分钟后哥哥到公园时，小明距公园还有1200米．已知哥哥骑车的速度是小明步行速度的3倍．小明步行每分钟走多少米．
<gadget id="calculator">3 * 10</gadget>
<output>30</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">1_200 / 20</gadget>
<output>60</output>

<result>60</result>