Answer: 3(4-x) + 6x = 4x + 12 - x
Step-by-step explanation:
For the solution to be all real numbers, the left hand has to be identical to the right hand side.
1) [tex]4(3-x)+7x=12-4x+7x=12+3x[/tex], so wrong.
2) [tex]4(4-x)+6x=16-4x+6x=16+2x[/tex], so wrong.
3) [tex]3(4-x)+6x=12-3x+6x=12+3x=4x+12-x[/tex], so correct.
4) Wrong variable, so eliminate immediately.
