new batch of "Ci Hai" is added to the bookstore. On the first day, 4 copies of the total (2/5) more are sold, and the remaining (5/8) are sold 3 less on the second day. If the number of copies of this batch of "Ci Hai" is not More than 30 copies, so how many copies of this batch of "Ci Hai" are left by the third day?
书店新进一批《辞海》，第一天售出总数的(2/5)多4本，第二天售出余下的(5/8)少3本，如果这批《辞海》的本数不超过30本，那么到第三天，这批《辞海》还剩多少本？
<gadget id="calculator">31 / 40</gadget>
<output>31/40 = around 0.775</output>

<gadget id="calculator">(31/40) * 20</gadget>
<output>31/2 = around 15.5</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(31/2) - (3/2)</gadget>
<output>14</output>

<gadget id="calculator">20 - 14</gadget>
<output>6</output>

<result>6</result>