Choice Dhoice C is the correct answer. This is a practical problem involving nice round numbers.

1. Start with the equation: $x + 47 = 100$
2. Subtract 47 from both sides: $x = 100 - 47$
3. Calculate: $x = 53$
4. Verify: $53 + 47 = 100$ ✓

💡 Mental Math: You can think of this as "what number plus 47 equals 100?" Counting up from 47 to 100 gives you 53.

Choice A is incorrect because this results from adding instead of subtracting: $100 + 47 = 147$. This is the wrong inverse operation.

Choice C is incorrect because this confuses the constant (47) with the solution. Just because 47 appears in the equation doesn't make it the answer.

Choice D is incorrect because this results from dividing: $\frac{100}{47} \approx 2.13$. Division is not relevant for this addition equation.