The bookstore has 2,100 copies of "Mathematics in Life", which sold 3/7 of the total in the morning and 40% of the total in the afternoon. How many books did the bookstore sell in total?
书店有《生活中的数学》2100本，上午卖出总数的(3/7)，下午又卖出总数的40%，这书店一共卖出几本书？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/7) + (2/5)</gadget>
<output>29/35 = around 0.828571</output>

<gadget id="calculator">2_100 * (29/35)</gadget>
<output>1_740</output>

<result>1_740</result>