Q#1 

                             3 < -5 - 2x <  9

Add +5 to all three sides:

                             3 < -5 - 2x <  9
                            +5   +5        +5
                          --------------------
                             8 <     -2x < 14 

Divide all three sides by -2, which reverses both
inequalities since we are dividing by a negative
number                          

                            8     -2x     14
                          ---- > ----- > ----
                           -2      -2     -2

                    or        -4 > x > -7

If you like you can write that in "mirror fashion" as

                              -7 < x < -4


Q#2 15<3x-3<24

                            15 < 3x - 3 < 24

Add +3 to all three sides:

                            15 < 3x - 3 < 24
                            +3       +3   +3
                          --------------------
                            18 < 3x     < 27 

Divide all three sides by 3, which DOES NOT reverse the
inequalities since we are dividing by a positive
number                          

                           18     3x     27
                          ---- < ---- < ----
                            3      3      3

                    or       6 < x < 9

Edwin