Xiaohua wants to write 25 brush characters, which have already been written (4/5), how many have been written.
小华要写25个毛笔字，已经写好了(4/5)，写好了多少个．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">25 * (4/5)</gadget>
<output>20</output>

<result>20</result>