The ratio of the numbers of A and B is 4:5, how much less is the number of A than the number of B
甲乙两数的比是4：5，甲数比乙数少多少
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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