The grain store brings in a batch of rice, sells 1/5 of the total number on the first day, and sells 20 bags more than the first day on the second day. At this time, the ratio of the number of sold bags to the number of remaining bags is 3 : 4. How many bags of this batch of rice?
粮店运进一批大米，第一天卖出总数的(1/5)，第二天比第一天多卖20袋，这时卖出的袋数与剩下的袋数的比是3：4，这批大米原有多少袋？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) * 2</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/7) - (2/5)</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">20 / (1/35)</gadget>
<output>700</output>

<result>700</result>