1. **State the problem:** Expand and simplify the expression $5n + 3(4 + 2n)$. 2. **Use the distributive property:** Multiply $3$ by each term inside the parentheses: $$3(4 + 2n) = 3 \times 4 + 3 \times 2n = 12 + 6n$$ 3. **Rewrite the expression:** Substitute back into the original expression: $$5n + 12 + 6n$$ 4. **Combine like terms:** Add the terms with $n$: $$5n + 6n = 11n$$ 5. **Final simplified expression:** $$11n + 12$$ This is the expanded and simplified form of the given expression.