Let the total budget be denoted as \( B \).
According to the problem, the friends spent 55% of their total budget on props. This can be expressed mathematically as:
\[ \text{Amount spent on props} = 0.55B \]
They also spent $369 on equipment, so the total amount spent on both equipment and props is:
\[ \text{Total amount spent} = 369 + 0.55B \]
Since the total amount spent cannot exceed the total budget, we set up the equation:
\[ 369 + 0.55B = B \]
To isolate \( B \), we can subtract \( 0.55B \) from both sides:
\[ 369 = B - 0.55B \]
This simplifies to:
\[ 369 = 0.45B \]
Next, we solve for \( B \) by dividing both sides by 0.45:
\[ B = \frac{369}{0.45} \]
Calculating this gives:
\[ B = 820 \]
Thus, the total budget for their student film is \( \boxed{820} \).
To verify:
- Amount spent on props: \( 0.55 \times 820 = 451 \)
- Total spent: \( 369 + 451 = 820 \) which matches the total budget. The calculations are correct.