Answer :
The given expression is
[tex]4x+9=-7x+42[/tex]First, we add 7x on each side
[tex]\begin{gathered} 4x+7x+9=-7x+7x+42 \\ 11x+9=42 \end{gathered}[/tex]Second, we subtract 9 from each side
[tex]\begin{gathered} 11x+9-9=42-9 \\ 11x=33 \end{gathered}[/tex]At last, we divide the equation by 11.
[tex]\begin{gathered} \frac{11x}{11}=\frac{33}{11} \\ x=3 \end{gathered}[/tex]