Answer:
9 (or 18)
9 (or 18)
18 (or 36)
Step-by-step explanation:
If B is midpoint if AC, then AB = BC
AB = 3x
BC = 5x - 6
So...
3x = 5x - 6
==> 2x = 6
==> x = 3
AB = BC = 3×3 = 5×3 - 6 = 9
And...
AC is AB + BC (since B is midpoint)
==> AC = 9 + 9 = 18
((Answer may be twice this. Picture is unclear if "3x" and "5x - 6" are values of AB and BC (resp.) or if they are midpoint values of AB and BC, in which case everything would just be doubled (except for x, the 2's would cancel out).))