Concept: The question tests on the application of absolute value.
Let the points be R,S,T and they have coordinates -a, b, c respectively.
r, s, t are the absolute values of the coordinates -a,b,c respectively.
With R being on the negative side of the number line would have,
=> -a (the coordinate in context)= -r
s = |b| = b
t = |c| = c
Thus the coordinates -a,b,c in terms of r, s, t are -r, s ,t respectively.
Hence average of the coordinates -a, b, c = -r + s + t /3 (Option e)
Pls note that the question asks you of the average of the coordinates