Speed of the exploration vehicle relative to the spaceship?

Question

A spacecraft approaching the earth launches an exploration vehicle. After the launch, an observer on earth sees the spacecraft approaching at a speed of 0.55c and the exploration vehicle approaching at a speed of 0.80c. What is the speed of the exploration vehicle relative to the spaceship?

Answer 1

The formula for the addition of velocities at relativistic speeds is v' = (u + v)/(1+(u/c)*(v/c))

Lets make things simpler by calculating the velocity as fraction of the speed of light c

vx * c= v

0.80 = (0.55 + vx) /(1+ 0.55*vx) = .......................................

(you should do the rest)

The result is about 0.446c.