Experimental Primary School held a "Book Donation Activity" to the children in the disaster area. The sixth grade students donated 200 books, 20% less than the fifth grade students, the fourth grade students donated 20% more than the fifth grade students, and the fourth grade students donated books. How many copies?
实验小学举行了一次向灾区小朋友"捐书献爱心活动"，六年级同学捐书200本，比五年级同学少捐20%，四年级同学比五年级同学多捐20%，四年级同学捐书多少本？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">200 / (4/5)</gadget>
<output>250</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">250 * (6/5)</gadget>
<output>300</output>

<result>300</result>