The number of A is less than the number of B (1/5), then the number of B is the number of A.
甲数比乙数少(1/5)，则乙数是甲数的多少．
<gadget id="calculator">1 / 5</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">1 / (4/5)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(5/4) * 1</gadget>
<output>5/4 = around 1.25</output>

<result>5/4 = around 1.25</result>