There is a document of 5,700 words. Due to time constraints, two typists A and B are arranged to start typing at the same time. A records 100 words per minute, and B records 90 words per minute. How long does it take to finish recording this document?
有一份5700字的文件，由于时间紧急，安排甲、乙两名打字员同时开始录入．甲每分钟录入100个字，乙每分钟录入90个字，录完这份文件需要多长时间？
<gadget id="calculator">100 + 90</gadget>
<output>190</output>

<gadget id="calculator">5_700 / 190</gadget>
<output>30</output>

<result>30</result>