The distance between AB and AB is 4800m. A lives in A, B and C live in B. One day, they set off from their place of residence at the same time, B and C went to A, and A went to B. After A and B meet, B immediately turns around and walks, and meets C after 10 minutes. On the second day, they set off at the same time again, but A was traveling in the opposite direction from the first day, but the speed of the three of them remained unchanged. B caught up with A and turned back immediately, but met C after 20 minutes. Given that A walks 40m per minute, find C's speed.
AB两地相距4800m，甲住A地，乙丙住B地．有一天，他们从住地同时出发，乙丙向A地前进，而甲向B地前进．甲乙相遇后，乙立即返身行进，10分钟后与丙相遇．第二天，他们又同时出发，只是甲行进的方向与第一天相反，但三人的速度没有改变，乙追上甲后立即返身行进，结果20分钟后与丙相遇．已知甲每分钟走40m，求丙的速度．
<gadget id="calculator">40 + 120</gadget>
<output>160</output>

<gadget id="calculator">4_800 / 160</gadget>
<output>30</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">2 / 40</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">120 * 10 * (1/20)</gadget>
<output>60</output>

<gadget id="calculator">120 - 60</gadget>
<output>60</output>

<result>60</result>