Transfer (1/5) of the number of people in the first group to the second group. The number of people in the two groups is the same. How much is the number of people in the second group smaller than the number of people in the first group?
把一组人数的(1/5)调到二组，两组人数一样多，原来二组人数比一组人数少多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5) - (1/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>