I don't know the options but I guess it would be something like this:
40,000 < x < 50,000
The length of an arc length can be calculated using the formula:
s = ra
where s is the lenght of the arc
and r is the radius of the circle
a is the central angle in radians
first converts degrees to radians
a = 60 ( pi / 180)
a = pi /3 =1.05
s = 21(1.05)
s = 22 mm is the length of the arc
Answer: x = -2
Step-by-step explanation:---------------