The school held a sports meeting. There were 28 participants in the third grade, three times the number of participants in the fourth grade, and 7 fewer participants in the fifth grade than the total number of participants in the third and fourth grades. How many people in the fifth grade participated in the competition?
学校举行运动会，三年级有28人参加比赛，四年级参加的人数是三年级的3倍，五年级参加的人数比三、四年级参加的总人数少7人．五年级参加比赛的有多少人？
<gadget id="calculator">28 * 3</gadget>
<output>84</output>

<gadget id="calculator">28 - 7</gadget>
<output>21</output>

<gadget id="calculator">84 + 21</gadget>
<output>105</output>

<result>105</result>