The relationship between the number of hours driven \( h \) and the total amount of miles driven \( m \) can be expressed with the following equation:
\[ m = 65h \]
This equation states that the total miles \( m \) is equal to the speed (65 miles per hour) multiplied by the number of hours driven \( h \).
To find out how far they drove after 7 hours, we can substitute \( h = 7 \) into the equation:
\[ m = 65 \times 7 \]
Calculating that gives us:
\[ m = 455 \]
So, they drove 455 miles after 7 hours.