The tortoise and the rabbit are running a race, the whole journey is 2000 meters, the tortoise climbs 25 meters per minute, and the rabbit runs 400 meters per minute. After running for a while, the rabbit felt that the speed of the tortoise was too slow, so he fell asleep. When the tortoise reached the finish line, the rabbit woke up and was still 800 meters away from the finish line. How long did the rabbit sleep?
龟、兔进行赛跑，全程为2000米，龟每分钟爬25米，兔每分钟跑400米．兔子跑了一会儿，觉得龟的速度太慢了，就睡了一觉，当龟到达终点了，兔子一觉醒来，离终点还有800米，问兔子睡了多少时间？
<gadget id="calculator">2_000 / 25</gadget>
<output>80</output>

<gadget id="calculator">2_000 - 800</gadget>
<output>1_200</output>

<gadget id="calculator">1_200 / 400</gadget>
<output>3</output>

<gadget id="calculator">80 - 3</gadget>
<output>77</output>

<result>77</result>