Question 811716

{{{ -6 <= 3x - 15 <=12}}}

{{{ -6+15 <= 3x - 15+15 <=12+15}}}

{{{ 9 <= 3x  <=27}}}

{{{ 9/3 <= 3x/3  <=27/3}}}

{{{ 3 <= x  <=9}}}