A rocket with a proper length of 1000 m moves in the +x direction at 0.6c with

Question:

A rocket with a proper length of 1000 m moves in the +x direction at 0.6c with respect to an observer on the ground. An astronaut stands at the rear of the rocket and fires a bullet toward the front of the rocket at 0.8c relative to the rocket. How long does it take the bullet to reach the front of the rocket

(a) As measured in the frame of the rocket,

(b) As measured in the frame of the ground, and