The fertilizer factory planned to produce 4,500 tons of fertilizer in 15 days, with an average daily output of 340 tons in the first 5 days, and then increased the output, and ended up completing the task 3 days ahead of schedule. How many tons of fertilizer will be produced on average every day in the next few days?
化肥厂计划用15天生产化肥4500吨，前5天平均每天生产340吨，后又提高了产量，结果提前3天就完了任务．求后几天平均每天生产化肥多少吨？
<gadget id="calculator">340 * 5</gadget>
<output>1_700</output>

<gadget id="calculator">4_500 - 1_700</gadget>
<output>2_800</output>

<gadget id="calculator">15 - 5 - 3</gadget>
<output>7</output>

<gadget id="calculator">2_800 / 7</gadget>
<output>400</output>

<result>400</result>