How to add results of two select commands in same query-Lemborco

By using union all clause two query can be combine into one and get one result.

Example

I currently have two select commands as per below. What I would like to do is to add the results together in the SQL query rather than the variables in code.

SELECT  SUM(totalHours) totalHours
FROM
        ( 
            select sum(hours) totalHours from resource
            UNION ALL
            select sum(hours) totalHours from projects-time
        ) s