Answer
Use the distributive property to remove the parenthesis
[tex]\begin{gathered} a(b+c) \\ ab+ac \end{gathered}[/tex]Now , Given
[tex]\begin{gathered} (x+7)12 \\ x\times12\text{ +7}\times12 \\ 12x+84 \end{gathered}[/tex]The final answer
[tex]12x+84[/tex]