Final answer:
To assign the value 'AC105' to a variable called flight_number in Python, you simply write: flight_number = 'AC105'. The Python language dynamically infers the variable's data type from the assigned value.
Step-by-step explanation:
To assign the value 'AC105' to a variable called flight_number in Python, you would write the following statement:
flight_number = 'AC105'
This line of code creates a variable named flight_number and assigns it the string value 'AC105'. In Python, you don't need to specify the data type of a variable; it is dynamically inferred from the value it is assigned.