asp classic - What’s wrong with this ASP Code; how would you fix it -

when run script says

microsoft vbscript runtime error '800a01f5'

illegal assignment: 'max_age'

/classic.asp, line 8

this script:

response.write(getmaxage()) function getmaxage()      const max_age = 50     dim irtnvalue      max_age = 45      irtnvalue = max_age      getstudentage = irtnvalue  end function 

you returning getstudentage instead of getmaxage. mean "getstudentage = irtnvalue"