In the sports meeting of the Young Eagle Summer Camp, 28 students participated in rock climbing, rope ladder, and swing. Equal to the number of people who participate in both rock climbing and rope ladders, how many people participate in all three sports?
雏鹰夏令营的运动会上，28名同学参加了攀岩、绳梯、秋千三项运动，每人至少参加两项运动，8人没有参加攀岩，参加攀岩的比参加秋千的多3人，参加秋千的等于既参加攀岩又参加绳梯的人数，则三项运动都参加的有多少人？
<gadget id="calculator">28 - 8 - 3</gadget>
<output>17</output>

<gadget id="calculator">28 - 8 - 17</gadget>
<output>3</output>

<gadget id="calculator">17 - 8 - 3</gadget>
<output>6</output>

<result>6</result>