The ratio of A and B is 4:5, A's number is 24, what is B's number?
甲、乙两数的比是4：5，甲数24，乙数是多少．
<gadget id="calculator">24 * 5</gadget>
<output>120</output>

<gadget id="calculator">120 / 4</gadget>
<output>30</output>

<result>30</result>