this is the correct way to solve these types of exercises
then we will try to do the same where a is (6+9x) and b is 24
[tex]|6+9x|\le24\longrightarrow-24\le6+9x\le24[/tex]and solve the right inequality for x
[tex]-24\le6+9x\le24[/tex]subtract 6 for all expression
[tex]\begin{gathered} -24-6\le6-6+9x\le24-6 \\ -30\le9x\le18 \end{gathered}[/tex]now divide on 9
[tex]\begin{gathered} -\frac{30}{9}\le\frac{9x}{9}\le\frac{18}{9} \\ \\ -\frac{10}{3}\le x\le2 \end{gathered}[/tex]ok, this means that the x values will be from -10/3 to 2 including these
Graph
solution is the red zone