Suppose You Observe a Collision of an Isolated System of Two

True/False

Suppose you observe a collision of an isolated system of two particles. A friend observes the same collision in a reference frame moving in the $+x$ direction with respect to yours. According to the Galilean transformation equations, on which aspects of the collision will you agree with your friend? (Answer T or F.)
-(c) On the value of the system's total $z$ -momentum