Anakin and Icema are 210 feet apart when they start walking toward one another. They are walking at the same speed, so whenever Anakin travels some number of feet, Icema travels the same number of feet. Let x represent the number of feet Anakin has traveled since he started walking toward Icema.
Write an expression in terms of x that represents the number of feet Anakin has walked toward Icema since they started walking.