[tex]\bf \boxed{-8}\stackrel{\textit{8 units}}{\rule[0.35em]{15em}{0.25pt}}0\stackrel{\textit{5 units}}{\rule[0.35em]{9em}{0.25pt}}\boxed{5}[/tex]
so there are 13 units in between, half of 13 is 6.5, so the point is 6.5 units from 5, and 6.5 units from -8.
5 - 6.5 = -1.5.
[tex]\bf \boxed{-8}\stackrel{\textit{}}{\rule[0.35em]{12em}{0.25pt}}\stackrel{\downarrow }{-1.5}\rule[0.35em]{1em}{0.25pt}0\stackrel{\textit{}}{\rule[0.35em]{9em}{0.25pt}}\boxed{5}[/tex]
