Classmates, have you heard the story of the cat and the mouse? One day, the cat found a mouse 20 meters in front of it, and it immediately chased after it. At the same time, the mouse found the cat and ran away immediately. The cat catches up with the mouse in 10 seconds at a speed of 7 meters per second, how many meters per second does the mouse run?
同学们，你们听说过猫和老鼠的故事吗？一天，猫发现一只老鼠在它前面20米的地方，它马上去追．同时老鼠发现猫，立刻就跑．猫以每秒7米的速度，用10秒追上老鼠，请问老鼠每秒跑多少米．
<gadget id="calculator">20 / 10</gadget>
<output>2</output>

<gadget id="calculator">7 - 2</gadget>
<output>5</output>

<result>5</result>