The duration of a physical education class is (2/3) hours, (1/5) of this class is used for warm-up exercises, (1/2) of this class is used for demonstration training, and the rest of the time is free for students to move around. What fraction of the class is the time for students to spend free time?
一节体育课的时间是(2/3)小时，做准备运动用了这节课的(1/5)，示范训练用了这节课的(1/2)，其余的时间学生自由活动．学生自由活动的时间是这节课的几分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/5) - (1/2)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>