The number of people in the first, second and third workshops of the printing factory is 12:8:21. There are 400 people in the first and second workshops. How many people are there in the third workshop?
印刷厂一、二、三车间人数比为12：8：21，一、二车间共有400人，三车间有多少人？
<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<gadget id="calculator">12 / 20</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">400 * (3/5)</gadget>
<output>240</output>

<gadget id="calculator">12 + 8 + 21</gadget>
<output>41</output>

<gadget id="calculator">12 / 41</gadget>
<output>12/41 = around 0.292683</output>

<gadget id="calculator">240 / (12/41)</gadget>
<output>820</output>

<gadget id="calculator">820 - 400</gadget>
<output>420</output>

<result>420</result>