Vasant Nanavati wrote...
Brute force :-):

=3DRIGHT(A2,LEN(A2)-FIND("/",SUBSTITUTE(A2,"-","/",
LEN(A2)-LEN(SUBSTITUTE(A2,"-",""))-1)))
..=2E.

You could save a function call and shorten this to

=3DMID(A2,FIND("=AC",SUBSTITUTE(A2,"-","=AC",
LEN(A2)-LEN(SUBSTITUTE(A2,"-",""))-1))+1,256)

but that leaves the quibble that if the string could contain any
characters, the robust approach would be an array formula like

=3DMID(A2,LARGE(IF(MID(A2,ROW(INDIRECT("1:256")),1 )=3D"-",
ROW(INDIRECT("1:256"))),2)+1,256)