MDX : Simple Substraction

Greetings Team !

Can some please advise how do i go about substracting a Member with current dimension  to calucalte age here ?

WITH  MEMBER [Admit Date] AS 
HEAD( FILTER([Time].[DATE].children , [Measures].[Admission Count] > 0 )).item(0).member_value

SELECT 
		{ 
			[Admit Date]
	    } ON 0 , 
	    
		(  [Patient].[Patient].&[X],
		   [Patient].[Patient Year of Birth].[Patient Year of Birth].Members
		 ) ON 1 
FROM   [<<Cube Name>>]	

Current OutpPut

              AdmitDate

X 1945    7/15/2004

I'm looking or an calculated Member AGE with substracts 1945 from 2004 .

              AdmitDate        AGe

X   1945   7/25/2004     59 ( 2004 - 1945 )

Thanks in advace for your help !

Rajkumar Yelugu