Question: The speed of a freight train is 8 mph less than the speed of a passenger train. The passenger train travels 400 miles in the same time that the freight train travels 360 miles. Find the speed of each train.
The speed of the passenger train is
The speed of the freight train is
1. **State the problem:**
We need to find the speeds of two trains: a passenger train and a freight train. The freight train's speed is 8 mph less than the passenger train's speed. The passenger train travels 400 miles, and the freight train travels 360 miles, both in the same amount of time.
2. **Define variables:**
Let $p$ be the speed of the passenger train in mph.
Then the speed of the freight train is $p - 8$ mph.
3. **Use the formula for time:**
Time = Distance \div Speed.
Since both trains travel for the same time, we set their times equal:
$$\frac{400}{p} = \frac{360}{p - 8}$$
4. **Solve the equation:**
Cross-multiply:
$$400(p - 8) = 360p$$
Distribute:
$$400p - 3200 = 360p$$
Subtract $360p$ from both sides:
$$400p - 360p - 3200 = 0$$
Simplify:
$$40p - 3200 = 0$$
Add $3200$ to both sides:
$$40p = 3200$$
Divide both sides by 40:
$$p = \frac{3200}{40}$$
Show cancellation:
$$p = \frac{\cancel{3200}^{80} }{\cancel{40}^{1}} = 80$$
5. **Find the freight train speed:**
$$p - 8 = 80 - 8 = 72$$
6. **Answer:**
The speed of the passenger train is $80$ mph.
The speed of the freight train is $72$ mph.