class of students participates in extracurricular group activities, and each person participates in at least one activity. Among them, the number of people participating in the long-distance running team accounts for (3/5) of the whole class, and the number of people participating in the chorus team accounts for (4/5). What percentage of the class does the group participate?
一个班同学参加课外小组活动，每人至少参加一项活动，其中参加长跑队的人数占全班人数的(3/5)，参加合唱队的占全班人数的(4/5)，两个小组都参加的人数占全班人数的几分之几？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) - 1</gadget>
<output>-1/5 = around -0.2</output>

<gadget id="calculator">(3/5) + (-1/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>