Two Satellites with Equal Rest Masses Are Traveling Toward Each

Multiple Choice

Two satellites with equal rest masses are traveling toward each other in deep space. One is traveling at 0.550c and the other at 0.750c. The satellites collide and somehow manage to stick
Together. What is the speed of the combined object after the collision?

A) 0.113c
B) 0.100c
C) 0.311c
D) 0.150c
E) 0.175c