The sixth grade of Central Primary School held a mathematics competition. The number of girls who participated in the competition was 28 more than that of boys. As a result, all boys won prizes, while only 75% of girls won prizes. The total number of prize winners was 42. How many people participated in the competition?
中心小学六年级举行数学竞赛，参加竞赛的女生比男生多28人，结果男生全部获奖，而女生获奖的只有75%，获奖的总人数是42人，问参加竞赛的一共有多少人？
<gadget id="calculator">42 - 21</gadget>
<output>21</output>

<gadget id="calculator">21 - 21</gadget>
<output>0</output>

<gadget id="calculator">1.75 + 0</gadget>
<output>1.75</output>

<gadget id="calculator">21 / 1.75</gadget>
<output>12</output>

<gadget id="calculator">12 + 28</gadget>
<output>40</output>

<gadget id="calculator">12 + 40</gadget>
<output>52</output>

<result>52</result>