How to compare the date in sqlite to give me the data which are lesser than 18days

 select 'Complaint' as 'type',(select count(*) from master_complaint where is_sent='1' and start_date < date('now','-18 day')) as 'syncd', (select count(*) from master_complaint where is_sent='0' and start_date < date('now','-18 day')) as 'notsyncd',
 'Failure' as 'type2',(select count(*) from master_failure where is_sent='1' and start_date < date('now','-18 day')) as 'syncd2', (select count(*) from master_failure where is_sent='0' and start_date < date('now','-18 day')) as 'notsyncd2'

in the above query i want to get the count of data which is less than 18 days from the start_date. this always gives me the following out put: