Yutian Township Primary School has the same number of students in the lower grades and middle grades, and the number of senior grades accounts for 35% of the total number of students in the school. There are 18 more students in the upper grades than in the middle grades. How many students are there in Yutian Township Primary School?
玉田乡小学低年级和中年级的人数相同，高年级人数是全校学生总数的35%，高年级比中年级多18人，玉田乡小学一共有学生多少人？
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">1 - (7/20)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">(13/20) / 2</gadget>
<output>13/40 = around 0.325</output>

<gadget id="calculator">(7/20) - (13/40)</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">18 / (1/40)</gadget>
<output>720</output>

<result>720</result>