Han and Clare walk towards each other at a constant rate, meet up, and then continue past each other in opposite directions. We will call the position where they meet up 0 feet and the time when they meet up 0 seconds. Han's velocity is 4 feet per second.
Clare's velocity is -5 feet per second.

Where is each person 10 seconds before they meet up?
When is each person at the position -10 feet from the meeting place?