In general, divide by 24 and format as hh:mm. But "decimal hours" come in
lots of flavors, like 1045, 10.45, 10.75 and 1075, all representing 10:45,
so you may have to adjust a little -or maybe a lot. See Chip Pearson's page http://www.cpearson.com/excel/datetime.htm for some theory on this.
Times are stored as a fraction of a 24 hour day (06:00 = 0.25,
12:00 = 0.5, 18:00 = 0.75, etc), so if you have a number of
hours, such as 14.5, dividing that by 24 converts it to an Excel
time value.