Dongxiang Farm plans to cultivate 6,420 hectares of land. It has been plowed for 5 days, with an average of 780 hectares per day. The rest will be plowed in 3 days, how many hectares will be plowed per day on average?
东乡农场计划耕6420公顷地．已经耕了5天，平均每天耕780公顷．剩下的要3天耕完，平均每天要耕多少公顷？
<gadget id="calculator">780 * 5</gadget>
<output>3_900</output>

<gadget id="calculator">6_420 - 3_900</gadget>
<output>2_520</output>

<gadget id="calculator">2_520 / 3</gadget>
<output>840</output>

<result>840</result>