7/9-11/18

If you meant the arithmetic expression 7/9 − 11/18, the result is 1/6.

Steps:

• Convert 7/9 to eighteenth: 7/9 = 14/18
• 14/18 − 11/18 = 3/18 = 1/6

If you meant dates (July 9 to November 18), please specify the year and whether you want the number of days in the span or something else. I can compute that too.