Teacher Cheng gave the students homework books. If it is only assigned to Group A, each student will get 30 copies; if only assigned to Group B, each student will get 15 copies; if only assigned to Group C, each student will get 10 copies; if only assigned to Group D, each student will get 15 copies Each person can get 20 copies. If it is divided equally among four groups of students, how many copies can each person get?
程老师给同学们分作业本．如果只分给甲组，每个同学可得30本；如果只分给乙组，每人可得15本；如果只分给丙组，每人可得10本；如果只分给丁组，每人可得20本．如果平均分给四个组的同学，每人可得几本？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/30) + (1/15) + (1/10) + (1/20)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / (1/4)</gadget>
<output>4</output>

<result>4</result>