Xiaoqiang used to write an average of 25 words per minute, but now he writes an average of 40 words per minute. How much has Xiaoqiang’s average writing volume per minute increased compared to before?
小强原来平均每分写字25个，现在平均每分写字40个．小强现在平均每分写字的数量比原来增加了多少
<gadget id="calculator">40 - 25</gadget>
<output>15</output>

<gadget id="calculator">15 / 25</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>