Answer:
1/21
Step-by-step explanation:
11 boys + 10 girls = 21 students
We want the ratio of coaches to students
1 coach: 21 students
1/21
<em>π</em> ≈ 3.14 > 2, so the second piece is the relevant one:

There is no picture given so I can’t see what the triangle is
I think it's the distributive property. I'm not sure. But I hope this helps.