There are 1,200 students in the first, second and third grades in a school, 300 in the first grade, the second grade accounts for 1/4 of the total number of the three grades, and what percentage of the third grades account for the total number of the three grades?
某校一二三年级1200人，一年级有300人，二年级的人数占三个年级总数的(1/4)，三年级的人数占三个年级总人数的百分之几？
<gadget id="calculator">300 / 1_200</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">1 - (1/4) - (1/4)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>