Question 916895
Are you trying to solve for x?


{{{-12-x=8-3x}}}
{{{-12-x+3x-8=8-3x+3x-8x}}}
{{{-20-4x=0}}}

{{{-4x-20+20=20}}}
{{{-4x=20}}}
{{{x=-(1/4)(20)}}}
{{{highlight(x=-5)}}}


Just simply using inverse operations and some commutative property of "addition".  Addition and multplication properties of equality govern every step, other than some included commutativity properties.