Hello! Hope I can assist you.
Let us simplify some terms first!
[tex]6m\cdot \:2n\cdot \:3 \ \textgreater \ 36mn[/tex]
[tex]3m\cdot \:3n\cdot \:2 \ \textgreater \ 2\cdot \:3^2mn[/tex]
[tex]8m\cdot \:2n\cdot \:3 \ \textgreater \ 48mn[/tex]
[tex]12m\cdot \:3n\cdot \:2 \ \textgreater \ 72mn[/tex]
[tex]36mn-2\cdot \:3^2mn+48mn+72mn[/tex]
From here, group like terms
[tex]36mn-2\cdot \:3^2mn+48mn+72mn[/tex]
[tex]\mathrm{Add\:similar\:elements:}\:36mn+48mn+72mn=156mn [/tex]
[tex]156mn-2\cdot \:3^2mn[/tex]
[tex]2\cdot \:3^2mn \ \textgreater \ 2\cdot \:9mn \ \textgreater \ 18mn[/tex]
[tex]156mn-18mn[/tex]
[tex]\mathrm{Add\:similar\:elements:}\:156mn-18mn=138mn[/tex]
Hope this helps!
