There are 20 female workers, and the ratio of male workers to female workers is 4:5. How many male workers are there?
女工有20人，男工与女工的比是4：5，男工人有多少人？
<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>