Part 1
If #(3x-24) < 0#
then #abs(3x-24) <= 27#
#rArr##color(white)("XXXX")##24-3x <= 27#
Adding #3x# to both sides
#color(white)("XXXX")##color(white)("XXXX")##24 <= 27 +3x#
Subtracting #27# from both sides
#color(white)("XXXX")##color(white)("XXXX")##-3 <= 3x#
Dividing by #3#
#color(white)("XXXX")##color(white)("XXXX")##-1 <= x#
Part 2
If #(3x-24) >= 0#
then #abs(3x-24) <= 27#
#rArr##color(white)("XXXX")##3x-24 <= 27#
Adding #24# to both sides
#color(white)("XXXXXXXX")##3x <= 51#
Dividing by #3#
#color(white)("XXXXXXXX")##x <= 17#
Combining Part 1 and Part 2
#color(white)("XXXX")##-1 <= x <= 17#