1. **State the problem:** Riley practices piano for 448 minutes in 4 weeks. We want to find a proportional equation for total practice time $t$ in terms of the number of days $d$. 2. **Understand the problem:** We know total time $t$ is proportional to days $d$, so $t = kd$ where $k$ is the constant of proportionality. 3. **Calculate $k$:** There are 4 weeks, each with 7 days, so total days = $4 \times 7 = 28$ days. 4. **Find $k$ by dividing total time by total days:** $$k = \frac{t}{d} = \frac{448}{28}$$ 5. **Simplify the fraction:** $$k = \frac{\cancel{448}}{\cancel{28}} = 16$$ 6. **Write the proportional equation:** $$t = 16d$$ **Final answer:** $t = 16d$