The elder brother and the younger brother set off from home to the library at the same time. The speed ratio of the elder brother and younger brother is 4:3. If the elder brother walks 100 meters per minute, how much does the younger brother walk per minute?
哥哥和弟弟同时从家出发到图书馆，哥哥和弟弟的速度比是4：3，哥哥每分钟走100米，则弟弟每分钟走多少．
<gadget id="calculator">100 / 4</gadget>
<output>25</output>

<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<result>75</result>