Two planets are on a collision course, heading directly toward each other at 0.250c. A spaceship sent from one planet approaches the second at 0.750c as seen by the second planet. What is the velocity of the ship relative to the first planet? (Explicitly show on paper how you follow the steps in the Problem-Solving Strategy for relativity, found on page 708 of the textbook. Your instructor may ask you to turn in this work.)