During the sixth grade mathematics interest group activities, the students who participated did not participate (3/7), and later 30 people participated, and the students who participated at this time did not participate (2/3). How many people are there in the sixth grade?
六年级数学兴趣小组活动时，参加的同学是未参加的(3/7)，后来又有30人参加，这时参加的同学是未参加的(2/3)，六年级一共有多少人？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">30 / (1/10)</gadget>
<output>300</output>

<result>300</result>