The duration of a class is (2/3) hours. In one science class, the teacher spent (1/5) hours on explanations, and (3/10) hours on group discussions. How long has it been?
一节课的时间是(2/3)小时，有一节科学课老师讲解用了(1/5)小时，小组讨论用了(3/10)小时，其余时间学生做实验，学生做实验用了多长时间？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/3) - (1/5) - (3/10)</gadget>
<output>1/6 = around 0.166667</output>

<result>1/6 = around 0.166667</result>