After transferring (1/5) of the number of people in class A to class B, the number of people in class A is equal, and the original number of people in class B is equal to the number of people in class A.
把甲班人数的(1/5)调入乙班后，则甲班人数相等，原来乙班人数是甲班人数的多少．
<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>