Lets try to design the possible number line first.
Tips:-
* keep A as constant.
* Mark C as C1 and C2 on the both sides of A. (C1 and C2 could be the possible location of C)
* Mark B as B1, B2, B3 and B4 where
B1 is extreme left to A, C1 and C2
B2 lies between C1 and A
B3 lies between A and C2
B4 lies extreme right to A, C1 and C2
Assumption: None of the point overlap each other.
So our number line would like something like this:-
------B1------C1------B2------A------B3------C2------B4------
Now by condition 1:
B = A + 3
This will rule out B1 and B2 from the above number line. So, our new number line would be something like this:-
-----------C1--------------A------B3------C2------B4------
B = C - 5
This will rule out C1 and B4 from the above number line. So, our new number line would be something like this:-
---------------------------A------B3------C2--------------
B lies between A and C. hence condition 1 is SUFFICIENT.
Condition 2:
Again draw the number line:
------B1------C1------B2------A------B3------C2------B4------
C = A + 8
This will rule out C1 from the above number line. So, our new number line would be something like this:-
------B1--------------B2------A------B3------C2------B4------
again C = B + 5, it means B <C> A
therefore, This will rule out B1, B2, and B4 from the above number line. So, our new number line would be something like this:-
---------------------------A------B3------C2--------------
B lies between A and C, hence condition 2 is also alone SUFFICIENT.
