There are four classes in the fifth grade of Hongxing Primary School. There are 154 students in classes 1, 2, and 3, and 156 students in classes 2, 3, and 4. Students in classes 1 and 4 account for 9/20 of the total number of students in the whole grade. How many students are there in fifth grade?
红星小学五年级有四个班，一、二、三班共有学生154人，二、三、四班共有学生156人，一、四班学生占全年级学生人数的(9/20)．五年级共有学生多少人？
<gadget id="calculator">156 + 154</gadget>
<output>310</output>

<gadget id="calculator">11 / 20</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(11/20) + (11/20) + (9/20)</gadget>
<output>31/20 = around 1.55</output>

<gadget id="calculator">310 / (31/20)</gadget>
<output>200</output>

<result>200</result>