1. **State the problem:** Simplify the expression $7y + 2y$. 2. **Formula and rules:** When adding like terms, add their coefficients and keep the variable part the same. 3. **Intermediate work:** $$7y + 2y = (7 + 2)y$$ 4. **Simplify:** $$= 9y$$ 5. **Explanation:** Since both terms have the variable $y$, we add the coefficients $7$ and $2$ to get $9$, then multiply by $y$. **Final answer:** $9y$