The number of students in the sixth grade is 60 less than the number of students in the whole school (1/5). It is known that there are 330 students in the sixth grade, and the number of students in the fourth and fifth grades is 1/3 of the total number of students in the school. How many students are there in the fourth and fifth grades?
六年级学生的人数比全校学生人数的(1/5)少60人，已知六年级有学生330人，四五年级的人数是全校人数的(1/3)，四五年级共有多少人？
<gadget id="calculator">330 + 60</gadget>
<output>390</output>

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

<gadget id="calculator">390 / (1/5)</gadget>
<output>1_950</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1_950 * (1/3)</gadget>
<output>650</output>

<result>650</result>