There are a bunch of candies, of which toffee accounts for 45%, and after adding 16 pieces of fruit candy, toffee only accounts for 25%. So, how many toffees are there in this pile of candies?
有一堆糖果，其中奶糖占45%，再放入16块水果糖后，奶糖就只占25%．那么，这堆糖中有奶糖多少块．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / (1/4)</gadget>
<output>4</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 / (9/20)</gadget>
<output>20/9 = around 2.222222</output>

<gadget id="calculator">4 - (20/9)</gadget>
<output>16/9 = around 1.777778</output>

<gadget id="calculator">16 / (16/9)</gadget>
<output>9</output>

<result>9</result>