Final answer:
The equation y = 5 + x represents the relationship between the days since Wendy set her watch (x) and the seconds behind (y).
Step-by-step explanation:
The given equation represents the relationship between the days since Wendy set her watch (x) and the seconds behind (y).
The equation is y = 5 + x, which means that the initial 5 seconds behind when Wendy set her watch are added to 1 second behind for each day that passes.