The school cafeteria burns 400 kilograms of coal in the first ten days of May, 50 kilograms less in the middle ten days of May, and the same amount of coal in the second ten days of May as in the middle ten days of May. How many kilograms of coal were burned in total in May?
学校食堂五月上旬烧煤400千克，中旬烧煤比上旬少50千克，下旬烧煤和中旬烧煤同样多．五月份一共烧煤多少千克？
<gadget id="calculator">400 - 50</gadget>
<output>350</output>

<gadget id="calculator">350 * 2</gadget>
<output>700</output>

<gadget id="calculator">700 + 400</gadget>
<output>1_100</output>

<result>1_100</result>