The sixth grade students of a certain school are divided into three batches to visit the science and technology museum. The ratio of the first batch to the second batch is 5:4, and the ratio of the second batch to the third batch is 3:2. It is known that the ratio of the first batch to the second , The sum of the three batches of people is less than 30 people, how many people are there in the sixth grade?
某校六年级学生分三批去参观科技馆，第一批和第二批的人数比是5：4，第二批与第三批的比是3：2，已知第一批比第二、三批人数的总和少30人，求六年级参观的有多少人？
<gadget id="calculator">18 - 15</gadget>
<output>3</output>

<gadget id="calculator">12 + 3</gadget>
<output>15</output>

<gadget id="calculator">30 / 15</gadget>
<output>2</output>

<gadget id="calculator">15 + 12 + 8</gadget>
<output>35</output>

<gadget id="calculator">2 * 35</gadget>
<output>70</output>

<result>70</result>