In a class, students spend 1/5 of their time on self-exploration, and 1/4 of the teacher's time on explanation. How much time do students spend on practice?
一堂课，学生自主探究时间占了(1/5)，教师讲解时间占了(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>