Choice Bhoice A is the correct answer.

1. Start with the equation: $4x + 8 = 40$
2. Subtract 8 from both sides: $4x = 40 - 8$
3. Simplify: $4x = 32$
4. Divide both sides by 4: $x = \frac{32}{4}$
5. Simplify: $x = 8$
6. Verify: $4(8) + 8 = 32 + 8 = 40$ ✓

Choice Bhoice D is incorrect because this results from adding 8 to 40: $48$, then $48/4 = 12$. Wrong inverse operation.

Choice Bhoice D is incorrect because this is the value of $4x$. You need to divide by 4.

Choice Bhoice C is incorrect because this results from multiplying 32 by 4: $128$.