The number A is (2/3), which is 20% less than the number B, and the number A is the number B.
甲数是(2/3)，比乙数少20%，甲数是乙数的多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) / 1</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>