1. **Problem:** Simplify the expression $ (3x + 5) + (2x + 7) $. 2. **Formula and rules:** When adding polynomials, combine like terms by adding their coefficients. 3. **Work:** $$ (3x + 5) + (2x + 7) = 3x + 5 + 2x + 7 $$ Combine like terms: $$ (3x + 2x) + (5 + 7) = 5x + 12 $$ 4. **Explanation:** We added the coefficients of $x$ terms: $3 + 2 = 5$, and the constants: $5 + 7 = 12$. 5. **Final answer:** $$ 5x + 12 $$