The school chorus is composed of fourth, fifth and sixth grade students. Among them, the fourth grade accounts for the total number (1/4), and the sixth grade accounts for the total number (2/5). What percentage of the total number of students are in the fifth grade?
学校合唱队由四、五、六年级学生组成．其中四年级占总人数的(1/4)，六年级占总人数的(2/5)．五年级占总人数的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>