The ratio of the number of calves to large calves is 4:5, which means how much fewer calves are than large calves.
小牛与大牛的头数比是4：5，表示小牛比大牛少多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>