Answer
$\left\{x|x \text{ is a real number}\right\}$
Work Step by Step
Distribute $3$ (on the left side of the equation) and combine like terms on the right side of the equation:
$3x-3= 3x-3$
Solve the equation to obtain:
$3x-3x=-3+3
\\0=0$
This is a true statement. Thus, any real number will satisfy the given equation.
The solution set is $\left\{x|x \text{ is a real number}\right\}$.