Create a formula field that calculates the Age in hours of the case that is displayed on the case page layout. The age of the case is defined as the difference in hours between the Date/Time opened and date/time closed for the case. If the case is still open, the age should calculate the difference between case creation and the current date/time. If the case is closed, the age should calculate the difference between the case closed date/time and the case created date/time. 

For eg: 1.5 hours if the case has been opened for an hour and a half.

Any suggestions???

Create a formula field that calculates the Age in hours of the case that is displayed on the case page layout. The age of the case is defined as the difference in hours between the Date/Time opened and date/time closed for the case. If the case is still open, the age should calculate the difference between case creation and the current date/time. If the case is closed, the age should calculate the difference between the case closed date/time and the case created date/time. 

For eg: 1.5 hours if the case has been opened for an hour and a half.

Any suggestions???