Hello im currently taking up Operating Systems and we're on unix ryt now. we have to make a script and here are the requirements.. can someone please help me. I would reli appreciate it.. because i dont reli know how to make scripts yet.

Name of script : parkingcharge.sh
Create a script that computes for the total parking charge of a customer. The following information are to be collected as inputs from the standard input :
Plate number (format : 7 characters, the first 3 are characters from ato z followed by a dash followed by a 3 digit number; i.e. : XXX-123)
Time in (format : military time; i.e. 1500 => 3 PM)
Time out (format : military time; i.e. 1900 => 7 PM)
Type of vehicle : can either be the following characeters: L, U or H which stands for Light vehicle, Utility vehicle or heavy vehicle respectively.
The parking lot operates starting at 7 AM and closes at 11:30 PM. The rates of the parking lot is as follows:
Standard parking fee (minimum of 2 hours) - 50 pesos
Succeeding hour or less in excess of 2 hours for :
Light vehicles - 5 pesos
Utility vehicles - 15 pesos
Heavy vehicles - 25 pesos
Futhermore, the maximum parking charge for the following vehicles applies:
Light vehicles - 100 pesos
Utility vehicles - 150 pesos
Heavy vehicles - 250 pesos
The script should be able to validate whether the time in and time out values are VALID inputs based on the value that is entered (time out > time in). Other validations are not to be filtered by the script. The output of the script is the parking charge of the vehicle and its details.
Sample run:
$ parkingcharge.sh
Please enter the plate number (i.e. : AAE-775) : XNY-123
Please enter the type of vehicle (L/U/H) : U
Please enter the time the vehicle entered the parking lot : 0845
Please enter the time the vehicle entered the parking lot : 1915
The vehicle with plate number XNY-123 was parked for 10 hours and 30 minutes. The parking charge for the vehicle is 150 pesos
Try again? : N
Sample run:
$ parkingcharge.sh
Please enter the plate number (i.e. : AAE-775) : GMA-111
Please enter the type of vehicle (L/U/H) : L
Please enter the time the vehicle entered the parking lot : 1245
Please enter the time the vehicle entered the parking lot : 1315
The vehicle with plate number XNY-123 was parked for 0 hours and 30 minutes. The parking charge for the vehicle is 50 pesos
Try again? : N
Note: Make sure the program keeps on repeating until the user enters ‘N' to quit the program.
Hint : You can use the following commands/control structure to complete your script : expr, if, test, for