In one class (2/3) hours, students spend (1/5) on their own exploration time, and (1/4) on teacher's explanation, how much time do students have for practice?
一堂课(2/3)小时，学生自主探究时间占了(1/5)，教师讲解占了(1/4)，学生练习时间还有几分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>