There are 2 spaceships, A and B, that approach the earth from opposite directions. Now according to an observer on spaceship A,she approaches the earth at 0.7c. According to an observer onspaceship B, he approaches the earth at 0.85c. What will be the speed of spaceship A according to an observer on spaceship B? Doesan observer on spaceship A measure a different or same value for the speed of spaceship B? Please also explain the steps.