Choice Bhoice D is the correct answer.

1. Start with the equation: $2x + 6 = 18$
2. Subtract 6 from both sides: $2x = 18 - 6$
3. Simplify: $2x = 12$
4. Divide both sides by 2: $x = \frac{12}{2}$
5. Simplify: $x = 6$
6. Verify: $2(6) + 6 = 12 + 6 = 18$ ✓

Choice Bhoice C is incorrect because this results from adding 6 to 18: $24$, then $24/2 = 12$. Wrong inverse operation.

Choice Bhoice C is incorrect because this is the value of $2x$. You need to divide by 2.

Choice Bhoice A is incorrect because this results from multiplying 12 by 2: $24$.