This question is simple I'm a little confused on the specifics so I will try my best to help.
s=θ(r)
arc length = angle x radius
2.46888m(or 8.1 ft) = (π/3) x r

Step-by-step explanation:
2(5) - 4(1) +3 =9
10 - 4 +3 = 9
4 is equal to 2*2 (double the 2 is 4)
Answer:
Step-by-step explanation:
If there needs to be 4 teachers per 21 students, you would divide the total amount of students by 21 and multiply that answer by 4. SO...:
84 ÷ 21 = 4 groups of 21 students.
4 groups × 4 teachers = 16
*** Answer***
16 TEACHERS