on the number line, point b is between points a and c. the distance between points a and b is 1/3 of ac.

Step-by-step explanation:
find distance of AC first
ac= √(y2-y1)²+(x2-x1)²
since there is no y we will consider it zero
so Ac= √(16-(-8))²
ac=24
ab is 1/3 of ac so it means
24*1/3=8
so ab is 8 units