Answer:
Y=t+5
Step-by-step explanation:
Bob starts running...(1)
Bill starts running 5 seconds later...(2)
From (1) and (2) we know that Bob had been running for 5 seconds when Bill started running.
The expression we are looking for is
Y=t+5
Y is the number of seconds Bob has been running
t is the number of seconds Bill has been running
Check the image for the diagram.