To find out how many miles the A train travels per hour, you can use the formula:
\[ \text{Miles per hour} = \frac{\text{Total miles}}{\text{Total hours}} \]
Plugging in the values:
\[ \text{Miles per hour} = \frac{300 \text{ miles}}{8 \text{ hours}} = 37.5 \text{ miles per hour} \]
So, the correct response is:
37.5 miles