Combine like terms on the right side of the equal sign:
7 - 3x = - 3x + 7
You can rearrange the right side to be:
7 - 3x = 7 - 3x
Because are the same thing, your answer ends up being all real numbers or infinitely many solutions. This means whatever number you plug in for the x-variable, the two sides will always be equal to each other.
