Using Longitude to Calculate Time

Time is calculated from 0⁰ longitude….Greenwich Mean Time.
For places east of GMT we add one hour for each time zone
For places west of GMT we subtract one hour for each time zone.
The earth rotates 360⁰ in 24 hours hence it rotates 15⁰ every hour and 1⁰ every 4 minutes.
Question: If it is noon at Greenwich Meridian what time is it at a place 75⁰ west.
Ans: 7 am (See below)