6x + 9 < 3 3x - 8 > 13
6x < 3 - 9 3x > 13 + 8
6x < - 6 3x > 21
x < -6/6 x> 21/3
x < -1 x > 7
solution is : x < -1 or x > 7
====================
4x + 5 > 25
4x > 25 - 5
4x > 20
x > 20/4
x > 5
===================
5 - 2x > = 27
-2x > = 27 - 5
-2x > = 22
x < = -22/2
x < = -11
==================
-2 < = x - 7 < = 11
-2 + 7 < = x - 7 + 7 < = 11 + 7
5 < = x < = 18
