You can put this solution on YOUR website! First of all, you need to convert your initial values to the units of your answer. So....
45 miles X 5280 feet / mile = 237600 feet
4 hours X 60 minutes / hour X 60 seconds / minute = 14400 seconds
SO.......
You have 237600 feet divided by 14400 seconds = 16.5 feet / second
Good luck!
JoeC