A and B jointly type a 7000-word manuscript at the same time. A typed 600 words per hour, and B typed 200 more characters per hour than A. After how many hours can the task be completed.
甲、乙两人同时合打一份7000字的稿件，甲每小时打600字，乙比甲每小时多打200字，经过多少小时可以完成任务．
<gadget id="calculator">600 + 200</gadget>
<output>800</output>

<gadget id="calculator">600 + 800</gadget>
<output>1_400</output>

<gadget id="calculator">7_000 / 1_400</gadget>
<output>5</output>

<result>5</result>