18) -x - 1 < 7 and - 6x - 9 = 8

Add 1 B.S.-
-x<8
Divide by -1 B.S.--
x>-8

AND

-6x-9>=8
Add +9 B.S.--
-6x>=17
Divide by -6 B.S.--
x<=-17/6


19) -3x + 8 = -5 or - 2x - 4 = -3

-3x+8<=-5
Subtract -8 B.S.--
-3x<=-13
Divide by -3 B.S.---
x>=13/3

AND

-2x-4>=-3
Add 4 B.S.--
-2x>=1
Divide by -2 B.S.--
x<=-1/2

20) -6x - 7 < -3 and - 8x = 3

-6x-7<-3
Add 7 B.S.--
-6x<4
Divide by -6 B.S.-
x>-4/6
i.e-
x>-2/3

AND

-8x>=3
Divide by -8 B.S.--
x<=-3/8

21) 9x - 9 = 9 and 5x > -1

9x-9<=9
Add +9 B.S.--
9x<=18
Divide by 9 B.S.--
x<=2

ANd

5x>-1
divide by 5 B.S.--
x>-1/5

22) -7x + 3 < -3 or - 8x = 2

-7x+3<-3
Subtract -3 B.S.--
-7x<-6
Divide by -7 B.S.-
x>6/7

OR

-8x>=2
Divide by -8 B.S.--
x<=-2/8
x<=-1/4

23) 3x - 5 < 4 and - x + 9 > 3

3x-5<4
Add 5 B.S.--
3x<9
Divide by 3 B.S.--
x<3

AND

-x+9>3
Subtract -9 B.S.--
-x>-6
Divide by -1 B.S.---
x<6

24) -8x - 6 < 5 or 4x - 1 = 3

-8x-6<5
Add 6 B.S.--
-8x<11
Divide by -8 B.S.--
x>-11/8

OR

4x-1>=3
Add 1 B.S.--
4x>=4
Divide by 4 B.S.--
x>=1

25) 9x + 3 = -5 or - 2x - 4 = 9

9x+3<=-5
Subtract -3 B.S.--
9x<=-8
Divide by 9 B.S.--
x<=-8/9

OR

-2x-4>=9
Add 4 B.S.--
-2x>=13
Divide by -2 B.s.---
x<=-13/2