There are 200 students in the fifth grade of the experimental primary school, which is 20% less than that in the fourth grade. How many students are there in the fourth grade?
实验小学五年级有学生200人，比四年级少20%，四年级有学生多少人？
<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>

<result>250</result>