In the experimental primary school, there are 15% more students in the fifth grade than in the fourth grade, 25% more in the fourth grade than in the third grade, and 91 more students in the fifth grade than in the third grade. How many students are there in the third grade?
实验小学的学生，五年级比四年级多15%，四年级比三年级多25%，而五年级学生比三年级多91人，三年级有学生多少人？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">(5/4) * (23/20)</gadget>
<output>23/16 = around 1.4375</output>

<gadget id="calculator">(23/16) - 1</gadget>
<output>7/16 = around 0.4375</output>

<gadget id="calculator">91 / (7/16)</gadget>
<output>208</output>

<result>208</result>