There are 4 classes in the fourth grade of a certain elementary school, among which there are 84 students in the first and second classes, and 136 students in the second, third and fourth classes. It is also known that the number of students in the second class is exactly 25% of the total number of students in the whole grade. How many people are there?
某小学四年级有4个班，其中一班、二班共84人，二班、三班和四班共136人，又知二班学生人数恰好是全年级人数的25%，该校四年级一共有多少人．
<gadget id="calculator">136 + 84</gadget>
<output>220</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">220 / (5/4)</gadget>
<output>176</output>

<result>176</result>