The school holds a sports meeting. There are 70 people in the fourth grade, half the number of participants in the third grade, and 50 people less than three times the number in the fifth grade. How many people in the fifth grade participate in the competition?
学校举行运动会．四年级有70人，三年级参加的人数是四年级的一半，五年级参加的人数是三年级的3倍少50人，五年级参加比赛的有多少人？
<gadget id="calculator">70 / 2</gadget>
<output>35</output>

<gadget id="calculator">35 * 3</gadget>
<output>105</output>

<gadget id="calculator">105 - 50</gadget>
<output>55</output>

<result>55</result>