The fifth grade of Yuhong Primary School held a mathematics competition. The number of girls participating in the competition was 28 more than that of boys. According to the results, all boys won prizes, while 25% of girls did not. The total number of winners was 42. It is also known that the number of people participating in the competition is the whole grade (2/3), how many fifth grade students are there in total?
育红小学五年级举行数学竞赛，参加竞赛的女生比男生多28人，根据成绩，男生全部获奖，而女生有25%的人未获奖，获奖获奖总人数是42人．又知参加竞赛的人数是全年级的(2/3)，五年级学生共有多少人？
<gadget id="calculator">25 / 100</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">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">52 / (2/3)</gadget>
<output>78</output>

<result>78</result>