1. 3x-5<19
3x-5+5<19+5
3x<24
3x/3<24/3
x<8
2. -2x+12<-4
-2x+12-12<-4-12
-2x<-16
-2x/-2>-16/-2
x>8
3. Because the numbers are positive when divided.
4. The inequality sign is reversed because the 2nd to last step is divided by by a negative number. (This is also the same for multiplication)
5. -7d+8>29
-7d+8-8>29-8
-7d/7>21/-7
d>-3
6.12-3b<9
12-12-3b<9-12
-3b/-3>-3/-3
b>1
7.z/7-6=>-5
z/7-6+6=>-5+6
z/7*7=>1*7
z=>7 (what grade are you in?!)
