The ratio of A and B is 4:5, A's number is 20, what is B's number?
甲、乙两数的比是4：5，甲数是20，乙数是多少．
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">20 * (5/4)</gadget>
<output>25</output>

<result>25</result>