Answer :
[tex]\mathbf{6x-18}[/tex]
1) Let' s x:
[tex]\mleft(2x-6\mright)+(4x-12)=[/tex]Remove the Parentheses:
[tex]2x-6+4x-12=[/tex]Combine like terms:
[tex]6x-18[/tex]2) Hence, the sum of this expression is:
[tex]\mleft(2x-6\mright)+(4x-12)=\mathbf{6x-18}[/tex]