There is a pile of candies, of which toffee accounts for 50%, and after adding 20 pieces of fruit candy, toffee only accounts for 40%. So, how many pieces of toffee are there in this pile of candies?
有一堆糖果，其中奶糖占50%，再放人20块水果糖后，奶糖就只占40%那么，这堆糖果中有奶糖多少块？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / (2/5)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / (1/2)</gadget>
<output>2</output>

<gadget id="calculator">(5/2) - 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 / (1/2)</gadget>
<output>40</output>

<result>40</result>