A Satellite Moves East, Taken as the Positive X Axis

Multiple Choice

A satellite moves east, taken as the positive x axis direction, at a speed of 0.5 c and a spaceship moves toward it (to the west) at a speed of 0.8 c as measured by an observer on the Earth. The speed of the satellite measured by an observer in the spaceship is

A) 8.7 c
B) 0.21 c
C) −0.21 c
D) 0.93 c
E) −0.93 c