Explanation:
For #1, if it says + you add the number of hours. Ex: Time in UTC 0 is 12:00, time in +3 is then 15:00 (3pm).
The same vice versa. Ex: Time in UTC 0 is 16:00 (4pm), in -2 it will be 14:00 (2pm).
For #2, +4 will be Friday at 22:00 (10pm) and for +7 it will be Saturday 1:00 (1am) etc.
Same for the - but it goes backwards
Hope that helps