If (1/5) of the number of people in group A is transferred to group B, the number of the two groups is exactly equal. It turns out that the number of people in Group B is the number of Group A
把甲组人数的(1/5)调入乙组，则两组人数正好相等．原来乙组人数是甲组的多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>