In a bag of sugar, toffee accounts for 25% of the total number. After putting in 20 pieces of fruit candy, toffee accounts for 20% of the total number. How many pieces of toffee are there?
一包糖，奶糖占总个数的25%，放入20块水果糖后，奶糖占总个数的20%，奶糖有多少块？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">80 * (1/4)</gadget>
<output>20</output>

<result>20</result>