A manuscript has 420 pages and is printed by two printers at the same time. A printer prints 5 pages per minute, and another printer prints 9 pages per minute. How many minutes will it take to print this manuscript?
一份稿件有420页，由两台打印机同时打印．甲台打印机每分钟打5页，乙台打印机每分钟打9页，几分钟可打印完这份稿件？
<gadget id="calculator">5 + 9</gadget>
<output>14</output>

<gadget id="calculator">420 / 14</gadget>
<output>30</output>

<result>30</result>