A batch of goods is shipped, (1/4) of the total number is shipped on the first day, and the rest (3/7) is shipped on the second day. At this time, there are still 1200 pieces left. Find the total number of pieces of this batch of goods.
运一批货物，第一天运了总数的(1/4)，第二天运了余下的(3/7)，这时还剩1200件，求这批货物的总件数．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1_200 / (4/7) / (3/4)</gadget>
<output>2_800</output>

<result>2_800</result>