The ratio of number A to number B is 5:3. If number A is 20, what is the number B?
甲数与乙数的比是5：3，如果甲数是20，那么乙数是多少．
<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>