Can Excel add working days to a date to result in another date?

For example, I need Excel to take the last day of a quarter (6/30) and add 10
working days resulting in the date of the 10th working day.

Use the WORKDAY function. These examples are from the Excel 97 help
entry for WORKDAY:

WORKDAY(DATEVALUE("01/03/91"), 5) equals 33248 or 01/10/91

If January 7, 1991 and January 8, 1991 are holidays, then:
WORKDAY(DATEVALUE("01/03/91"), 5, {33245, 33246}) equals 33252
or 01/14/91