On Sunday morning, both elder brother and younger brother are going to grandma's house. The younger brother goes 5 minutes first, and the older brother catches up with the younger brother 25 minutes after starting. If the elder brother walks 5 meters more per minute, he can catch up with the younger brother 20 minutes after departure. How many meters does the younger brother walk per minute?
星期天早晨，哥哥和弟弟都要到奶奶家去．弟弟先走5分，哥哥出发后25分追上弟弟．如果哥哥每分多走5米，那么出发后20分就可以追上弟弟．弟弟每分走多少米？
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">25 / 20</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">25 + 5</gadget>
<output>30</output>

<gadget id="calculator">30 / 25</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(5/4) - (6/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">5 / (1/20)</gadget>
<output>100</output>

<result>100</result>