1. **State the problem:** Solve the equation $5y + 8y = 784$ for $y$. 2. **Combine like terms:** Since both terms on the left side have $y$, add their coefficients: $$5y + 8y = (5 + 8)y = 13y$$ 3. **Rewrite the equation:** $$13y = 784$$ 4. **Isolate $y$ by dividing both sides by 13:** $$y = \frac{784}{13}$$ 5. **Simplify the fraction:** $$y = \cancel{\frac{784}{13}} = 60.3076923...$$ Since $784$ divided by $13$ equals $60.3076923...$, the exact fraction form is preferred: $$y = \frac{784}{13}$$ 6. **Final answer:** $$y = \frac{784}{13}$$