Concept: The question tests on the basics of Absolute values
Solution:
2b-6=8
=>b=7 or
- (2b-6)= 8
=> b=-1 (Using the fundamental concept of Absolute values
=> |x-a| = x-a if x>=a & (a-x )if x < a
According to the question, you can also say that |2b-6| = 8 implies that the distance between b and 3 is equal to 4 implying that b could be -1 or 7.