How to subtract 2 dates in oracle to get the result in hour and minute

Question

I want to subtract 2 dates and represent the result in hour and minute in one decimal figure.

I have the following table and I am doing it in this way but the result

Answer 1

This query is very usefull for me and if any body want diffrence between start_date and end_date with time like HH:MI:SS please use this query.

SELECT
    TRIM(TO_CHAR(TRUNC(((86400*(end_date - start_date))/60)/60)-24*(trunc((((86400(end_date - start_date))/60)/60)/24)),'00')) ||'.'||
    TRIM(TO_CHAR(TRUNC((86400*(actual_completion_date - actual_start_date))/60)-60*(trunc(((86400*(end_date - start_date))/60)/60)),'00')) ||'.'||
    TRIM(TO_CHAR(TRUNC((86400*(end_date - start_date)))-60*(trunc((86400*(end_date - actual_start_date))/60)),'00')) as duration  
FROM fnd_concurrent_requests;