using interval in a query with a column for the interval value?

I am writing a script and I need to output results to a file based on a
table where the data to select is based on a 'last' date and an
'interval'.

Essentially

Name
Last_date
Interval

Jed 2005-06-02 30
Tom 2005-08-02 30

Select name
>From table1
Where last_date < now() - [[interval days]];

The interval days part is what is stumping me I need to say "now() -
interval '30 days'" but I need to use the interval column.

How do I make this work?

Thanks,

Jed