Xiao Ming went from the bottom of the mountain to the top of the mountain and then went down the same way. The speed when going up the mountain is 25 meters per minute, and it took 40 minutes to climb to the top of the mountain. It only took 20 minutes to go down the mountain. What was the speed when going down the mountain?
小明从山下到山顶后又原路下山．上山时的速度是25米/分，用了40分钟爬到山顶．下山时只用了20分钟，下山时速度是多少？
<gadget id="calculator">40 / 20</gadget>
<output>2</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>