Please help me solve this problem

iv, ii, i, iii, vi, v

Step-by-step explanation:

First, it is better if you fix all of these into fractions:

2/3--> 0.6666

-4/5--> -0.8

7/4--> 1.75

-21/8--> -2.625

11/4--> 2.75

root 5--> 2.24...

Hope this helps!!

arc length = radius * x ( in radians)

6 * pi = 18 * x

divide by 18 on each side

6 pi / 18 = x

pi/3 = x

the angle is pi / 3 radians

or   60 degrees