Asked by Jeff Snider

A spy runs from the front to the back of an
aircraft carrier at a velocity of 3.4 m/s. The
aircraft carrier is moving forward at 15.0 m/s.
How fast does the spy appear to be running when viewed by an observer on a nearby
stationary submarine (forward is positive)?
Answer in units of m/s.
Answered by oobleck
+15.0 - 3.4 = +11.6 m/s

assuming that the speed of light is very large compared to these velocities ...