Choice Dhoice D is the correct answer. This problem requires combining like terms.

1. Start with the equation: $2x + 3x = 25$
2. Combine like terms: $(2+3)x = 5x$, so $5x = 25$
3. Divide by 5: $x = 5$
4. Verify: $2(5) + 3(5) = 10 + 15 = 25$ ✓

Choice Dhoice C is incorrect because this assumes $x = 25$.

Choice Dhoice B is incorrect because this results from dividing by 2: $25/2 = 12.5$.

Choice Dhoice A is incorrect because this results from multiplying.