Answer
The statement does not make sense.
Work Step by Step
We know that for an angle less than $4\pi $ , we can find the terminal angle less than $2\pi $ because when an angle exceeds $4\pi $, adding it with $2\pi $ will make it greater than $4\pi $ and subtracting it with $2\pi $ will make it greater than $2\pi $.
Hence, it is not always true that adding or subtracting $2\pi $ to an angle gives a coterminal angle less than $2\pi $.
