Hope Elementary School held a mathematics competition for the third grade. The number of girls participating in the competition was 28 more than the number of boys. According to the results, all boys were listed as excellent, and girls (1/4) did not achieve excellent results. The total number of male and female students who achieved excellent results There are 42 students. The number of male and female students participating in the competition accounts for 20% of the total number of students in the whole grade. How many students are there in the third grade?
希望小学举行三年级数学竞赛，参加竞赛的女生人数比男生人数多28名，根据成绩，男生全部列为优良，女生则有(1/4)没有达到优良成绩，男女生取得优良成绩的总人数是42名，参加比赛的男女生人数占全年级总人数的20%，求三年级共有学生多少人？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">28 * (1/4)</gadget>
<output>7</output>

<gadget id="calculator">42 - 28</gadget>
<output>14</output>

<gadget id="calculator">7 + 14</gadget>
<output>21</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 + (3/4)</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">21 / (7/4)</gadget>
<output>12</output>

<gadget id="calculator">12 + 28 + 12</gadget>
<output>52</output>

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

<gadget id="calculator">52 / (1/5)</gadget>
<output>260</output>

<result>260</result>