batch of rice was shipped from the school cafeteria, and 7/20 of the total was eaten in the first week, and 500 kg was eaten in the second week, leaving 540 kg. How many kg of this batch of rice are there?
校食堂运来一批大米，第一周吃了总数的(7/20)，第二周吃了500千克，还剩下540千克，这批大米共有多少千克．
<gadget id="calculator">500 + 540</gadget>
<output>1_040</output>

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">1 - (7/20)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1_040 / (13/20)</gadget>
<output>1_600</output>

<result>1_600</result>