class lasts 40 minutes, the teacher spends (1/5) hour explaining, the students spend (3/10) hours doing experiments, and the rest of the time students do homework independently. How many hours did the students spend on independent homework? What is the column
一节课40分钟，老师讲解用了(1/5)小时，学生做实验用了(3/10)小时，其余的时间学生独立做作业．学生独立做作业用了多少小时？列式为多少
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

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

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

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