Choice Dhoice C is the correct answer.

1. Start with the equation: $6x + 4 = 28$
2. Subtract 4 from both sides: $6x = 28 - 4$
3. Simplify: $6x = 24$
4. Divide both sides by 6: $x = \frac{24}{6}$
5. Simplify: $x = 4$
6. Verify: $6(4) + 4 = 24 + 4 = 28$ ✓

Choice Dhoice D is incorrect because this results from adding 4 to 28: $32$, then $32/6 \approx 5.33$. Wrong inverse operation.

Choice Dhoice A is incorrect because this is the value of $6x$. You must divide by 6 to finish.

Choice Dhoice B is incorrect because this results from multiplying 24 by 6: $24 \times 6 = 144$.