You and Mae are in free-float frames. Mae has just passed you, traveling at a speed of 60 km/hr. You throw a ball toward her at a speed of 60 km/hr. What will Mae see the ball doing?
The ball will be stationary, floating freely in her own reference frame.
She'll see the ball coming toward her at 120 km/hr.
She'll see the ball moving away from her at 60 km/hr.
She'll see the ball coming toward her at 60 km/hr.