The ratio of the two numbers of A and B is 5:4, so how much less is B than A.
甲乙两数的比是5：4，那么乙比甲少多少．
<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>