Let the time of the bus ride be represented by \( x \). According to the problem, the total travel time is the sum of the bus ride time and the walking time. Tran walked for 30 minutes, which is equivalent to \( \frac{1}{2} \) hours.
The total travel time can be expressed as:
\[ x + \frac{1}{2} \]
It is given that the total travel time was 4 times the duration of the bus ride, which can be expressed as:
\[ 4x \]
Now we can set up the equation:
\[ x + \frac{1}{2} = 4x \]
This equation models the situation described.