Give A's (1/5) to B. At this time, A and B are equal. It turns out that B is much less than A.
把甲的(1/5)给乙，这时甲、乙相等，原来乙比甲少多少．
<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>

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

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