[1.04] If B is between A and C, AB=2x-1, BC=3x+5 and AC=24, what is the value of AB?

Segment A C contains point B.

Note that point B is in segment AC, therefore we can say that the sum of lengths of AB and BC is equal to AC, or

AB + BC = AC
Substituting,
(2x - 1) + (3x + 5) = 24
5x + 4 = 24
5x = 20
x = 4
Thus,
AB: 2(4) - 1 = 7 units

Hope this helps~ :3