To simplify the expression \(-45x + 12x - 30x\), we combine the like terms (the terms that have \(x\)):
\[ -45x + 12x - 30x = (-45 + 12 - 30)x \]
Calculating the coefficients:
\[ -45 + 12 = -33 \] \[ -33 - 30 = -63 \]
Now, we have:
\[ -63x \]
Thus, the simplified expression is:
\[ -63x \]