Li Wei walked 400 meters from home yesterday to buy a newspaper, and then walked 600 meters to the supermarket to buy a bottle of detergent, which took 20 minutes. His average speed is how many meters per minute.
李伟昨天先从家出发走了400米买了张报纸，然后又走了600米去超市买了一瓶洗涤剂，共用了20分钟．他的平均速度是每分钟行多少米．
<gadget id="calculator">400 + 600</gadget>
<output>1_000</output>

<gadget id="calculator">1_000 / 20</gadget>
<output>50</output>

<result>50</result>