How to get answer/Answer by mimiwhatsup:
[tex]12-3x=12-3x\\\mathrm{Subtract\:}12\mathrm{\:from\:both\:sides}\\12-3x-12=12-3x-12\\Simplify\\-3x=-3x\\\mathrm{Add\:}3x\mathrm{\:to\:both\:sides}\\-3x+3x=-3x+3x\\Simplify\\Both\:sides\:are\:equal\\[/tex]
Answer: B) all real numbers
