enumeration in if statement

Hi,

entity with attribute enumeration agerange : with values young and old.

and age (decimal)

what is the if statement in create object to change age to 10 if agerange is young and age is 60 when agerange  is old  in

tried:

if $member/agerange = young
then 10
else 100

but get error mismatched input 'then'expecting '9'('

probably have ta add some ( ..