Nested sql query with filtering by date?

Question

PostgreSQL

Hello everyone, I would like to ask you to help me with this request.
There is a client with which tasks are associated (by client id ), tasks can be both open and closed
Romashka LLC {
name closing date
Task # 1 2019-10-01
Task # 2 null
Task # 3 2019-07-01
}
Needed display a list of all clients whose last task has been closed for more than 60 days.
Here is a query:

select DISTINCT AC.name,ACTIV.name,(extract(day from now() - ACTIV.datefinish)) from sys_accounts AC RIGHT JOIN sys_activities ACTIV ON ACTIV.account_guid=AC.guid WHERE (extract(day from now() - ACTIV .datefinish))>60

But how to count days in it exactly from the last closed task in each specific client?