A and B set off from A and B respectively at the same time, and walk toward each other at a constant speed. After walking for 1 minute, the distance between them is 150 meters closer. After another 20 minutes, they are at the midpoint of the distance between A and B. If they meet at 168 meters, what is the difference in the distance traveled by the two of them per minute?
甲、乙分别从A、B两地同时出发，相向而行，匀速前进，行了1分钟，两人间的距离近了150米，再过20分钟，他们在离A、B两地路程中点168米处相遇，他们两人每分所行路程的差是多少．
<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">2 / 21</gadget>
<output>2/21 = around 0.095238</output>

<gadget id="calculator">168 * (2/21)</gadget>
<output>16</output>

<result>16</result>