The teaching building of Ningcheng Primary School covers an area of 640 square meters, which is about (4/45) of the total area of the campus. Find the total area of Ningcheng Primary School campus.
宁城小学教学楼占地面积是640平方米，大约是校园总面积的(4/45)．求宁城小学校园的总面积．
<gadget id="calculator">4 / 45</gadget>
<output>4/45 = around 0.088889</output>

<gadget id="calculator">640 / (4/45)</gadget>
<output>7_200</output>

<result>7_200</result>