Reference Frames and Relative Motion Practice Test

A train moves east at $20\ \text{m/s}$ relative to the ground. A passenger walks west at $2\ \text{m/s}$ relative to the train. What is the passenger’s velocity relative to the ground?

Two drones fly east relative to the ground: Drone X at $15\ \text{m/s}$ and Drone Y at $15\ \text{m/s}$. In Drone Y’s reference frame, what is Drone X’s velocity?