Answer: u=7
Given:
[tex]-6u+3(u-3)=12[/tex]- Distribute 3(u-3):
[tex]\begin{gathered} -6u+3(u-3)=12 \\ \Rightarrow-6u+3u-9=12 \end{gathered}[/tex]- Combine like terms:
[tex]\begin{gathered} \begin{equation*} -6u+3u-9=12 \end{equation*} \\ \Rightarrow-6u+3u=12+9 \\ \Rightarrow-3u=21 \end{gathered}[/tex]- Divide both sides by -3:
[tex]\begin{gathered} \begin{equation*} -3u=21 \end{equation*} \\ \Rightarrow\frac{-3u}{-3}=\frac{21}{-3} \\ \Rightarrow u=7 \end{gathered}[/tex]Therefore, u=7.
