There is a batch of paint, 840 barrels were sold on the first day, and less (2/7) was sold on the second day than on the first day. How many barrels were sold in total in the two days?
有一批涂料，第一天卖出840桶，第二天比第一天少卖(2/7)，两天一共卖出多少桶？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">840 * (5/7)</gadget>
<output>600</output>

<gadget id="calculator">600 + 840</gadget>
<output>1_440</output>

<result>1_440</result>