Answer:
135° (degrees)
Step-by-step explanation:
The Earth rotates 360° in about 24 h
How many degrees in 1 hour

So, in 1 hour the Earth rotates 15 degrees. This means that a person would have to reset their watch by 1 hour after travelling 15 degrees
In 9 hours

So, a person would have to travel 135 degrees in order to reset their watch by 9 hours.