Final answer:
In mathematics, a variable is a quantity that can vary. To convert the number of revolutions into radians, multiply it by 2π. Therefore, the converted variable expression would be x = 2πr0.
Step-by-step explanation:
In mathematics, a variable is a quantity that can vary or assume different values. In the given equation, x is the variable. To convert the number of revolutions into radians, multiply it by 2π since there are 2π radians in one revolution. Therefore, the converted variable expression would be x = 2πr0.