There are 180 girls in the sixth grade of Yuhong Primary School, accounting for 45% of the whole grade. The number of students in grade six accounts for 20% of the total number of students in the school. How many students are there in the school?
育红小学六年级有女生180人，占全年级人数的45%．六年级学生人数占全校人数的20%．全校一共有学生多少人？
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">180 / (9/20) / (1/5)</gadget>
<output>2_000</output>

<result>2_000</result>