In order to support poor mountainous areas, the fifth grade donated 200 books, equivalent to (4/5) the number donated by the sixth grade. How many books are donated less than the sixth grade?
为支援贫困山区，五年级捐出图书200本，相当于六年级捐出本数的(4/5)，比六年级少捐书多少本？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">250 - 200</gadget>
<output>50</output>

<result>50</result>