The former term of the ratio is reduced to the original (1/2), and the latter term is expanded by 5 times, so how much is the ratio reduced to the original
比的前项缩小到原来的(1/2)，后项扩大5倍，那么比值缩小到原来的多少
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">2 / 45</gadget>
<output>2/45 = around 0.044444</output>

<gadget id="calculator">(4/9) / (2/45)</gadget>
<output>10</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>