There are 45 students in Class 5 and 1 of the Experimental Primary School. Among them, those who participate in the science and technology group account for 1/5 of the class, and those who participate in the sports group account for 3/10 of the class. The rest of the students participate in the reading group. How many reading groups account for the whole class.
实验小学五1班共有学生45人，其中参加科技小组的占全班人数的(1/5)，参加体育小组的占全班人数的(3/10)，剩下的学生参加阅读小组，参加阅读小组的占全班人数的多少．
<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">1 - (1/5) - (3/10)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>