Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: the average marks of a class of 35 students is 45 and that of another class of 55 students is 65 . find the average marks of all the students ?
57
53.64 (rounded to two decimal places)