All the students in the sixth grade went to the autumn tour in batches, the first batch went to the total number (2/5), and the second batch had 65 fewer students than the first batch. At this time, the ratio of the number of people who have already gone to the autumn tour to the number of those who have not yet gone to the autumn tour is 3:4. How many students are there in the sixth grade?
六年级全体学生分批去秋游，第一批去了总数的(2/5)，第二批去的人数比第一批少65人．这时已经去秋游的人数和未秋游人数的比是3：4，六年级共有学生多少人？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) - (1/35)</gadget>
<output>13/35 = around 0.371429</output>

<gadget id="calculator">65 / (13/35)</gadget>
<output>175</output>

<result>175</result>