Converting interval to decimal ?

Is there a way to convert an hour to minutes interval to a decimal value for a report ? . I am running a 4gl prog that reports hors worked in the interval form of ( 8:40 ) for eigth hors and forty minutes and I want to display it as 8.66 hours . I have worked a solution with awk but would prefer to do it with 4gl code . Thanks in advance , Chago