Choice Dhoice D is the correct answer.

1. Start with the equation: $9x - 27 = 18$
2. Add 27 to both sides: $9x = 18 + 27$
3. Simplify: $9x = 45$
4. Divide both sides by 9: $x = \frac{45}{9}$
5. Simplify: $x = 5$
6. Verify: $9(5) - 27 = 45 - 27 = 18$ ✓

Choice Dhoice A is incorrect because this results from subtracting 27 from 18: $-9$, then $-9/9 = -1$. We must add to undo subtraction.

Choice Dhoice C is incorrect because this is the value of $9x$. Don't stop early!

Choice Dhoice C is incorrect because this results from multiplying 45 by 9: $405$.