Downhill Speed D11Cb6
1. **State the problem:** Jamal rides 6 miles downhill to the skate park and returns uphill on the same trail. His uphill speed is 1 mile per hour slower than his downhill speed. The return trip takes 1 hour longer than the trip to the park. We need to find his downhill speed.
2. **Define variables:** Let $d$ be the downhill speed in miles per hour.
3. **Write expressions for time:**
- Time downhill = distance / speed = $\frac{6}{d}$ hours
- Uphill speed = $d - 1$ miles per hour
- Time uphill = $\frac{6}{d - 1}$ hours
4. **Set up the equation using the time difference:**
$$\frac{6}{d - 1} - \frac{6}{d} = 1$$
5. **Solve the equation:**
Multiply both sides by $d(d - 1)$ to clear denominators:
$$6d - 6(d - 1) = d(d - 1)$$
Simplify left side:
$$6d - 6d + 6 = d^2 - d$$
Which reduces to:
$$6 = d^2 - d$$
Rewrite as a quadratic equation:
$$d^2 - d - 6 = 0$$
6. **Factor the quadratic:**
$$(d - 3)(d + 2) = 0$$
7. **Find the roots:**
$d = 3$ or $d = -2$
8. **Choose the valid speed:** Speed cannot be negative, so $d = 3$ miles per hour.
**Final answer:** Jamal's downhill speed is $\boxed{3}$ miles per hour.