There are 6 time zones in the US: Hawaiian, Alaskan, Pacific, Mountain, Central, and Eastern. To figure out the time in different zones start with what you know: It's 10 am in the Eastern zone, and LA is in Pacific time. Now go back to the list and count backwards from Eastern to Pacific: 3. For each different time zone subtract 1 from 10: 10-3=7. In LA it would be C. 7 am :)
