1. **State the problem:**
We have two trains making the same trip. The passenger train takes 3 hours, and the freight train takes 7 hours. The freight train's speed is 40 miles per hour less than the passenger train's speed. We need to find the rate (speed) of each train.
2. **Define variables:**
Let $r_p$ be the rate of the passenger train (in miles per hour).
Let $r_f$ be the rate of the freight train.
3. **Write the relationships:**
Since the freight train's rate is 40 mph less than the passenger train's rate:
$$r_f = r_p - 40$$
4. **Use the formula for distance:**
Distance $d = \text{rate} \times \text{time}$.
Both trains travel the same distance, so:
$$d = r_p \times 3 = r_f \times 7$$
5. **Substitute $r_f$ in terms of $r_p$:**
$$3r_p = 7(r_p - 40)$$
6. **Solve for $r_p$:**
$$3r_p = 7r_p - 280$$
Move terms to one side:
$$3r_p - 7r_p = -280$$
$$-4r_p = -280$$
Divide both sides by $-4$:
$$r_p = \frac{-280}{-4}$$
$$r_p = 70$$
7. **Find $r_f$:**
$$r_f = r_p - 40 = 70 - 40 = 30$$
8. **Check the distance:**
Passenger train distance:
$$d = 70 \times 3 = 210$$
Freight train distance:
$$d = 30 \times 7 = 210$$
Both distances are equal, confirming the solution.
**Final answer:**
- Passenger train rate: $70$ mph
- Freight train rate: $30$ mph
Train Rates 6D5C50
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