The number of male workers in a workshop is twice the number of female workers. If 21 male workers are transferred, the ratio of female workers to male workers is 2:1. How many female workers are there in this workshop?
某车间男工人数是女工人数的2倍，若调走21个男工，那么女工人数与男工人数的比是2：1．这个车间的女工有多少人？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 - (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">21 / (3/2)</gadget>
<output>14</output>

<result>14</result>