Function description

dear all, 

Ive a data set in which age of the subject is given as an attribute and the values  are given in
either months  or years or  in weeks.  

eg:  3 days ,   8 weeks ,  10 months

I want to convert that attribute in to no. of days, so that i can group them based on no. of days.   I was trying
to use functions - 'finds" and "parse", but not successful.  can someone helps me on this. thank you.

regds
thiru