The tortoise and the hare run a race, they walk towards each other on a small road 1000m apart, the rabbits run 32.5m per minute, and they meet after 20 minutes. How many meters does the tortoise run per minute? (solution by equation)
龟兔赛跑，它们在相距1000m的小路上相向而行，兔子每分钟跑32.5m，20分钟后相遇．乌龟每分钟跑多少米？(用方程解)
<gadget id="calculator">1_000 / 20</gadget>
<output>50</output>

<gadget id="calculator">50 - 32.5</gadget>
<output>17.5</output>

<result>17.5</result>