Readmission Query for Access 2007

[nycpeach]

I have to design a query that details the # of patients readmitted to a hospital within 30 days of their last discharge.
Each patient has a separate record in the database for each visit.
For example,

Table:Inpatient
Record Number AdmitDate DischDate
1683 2/3/10 4/8/11
1683 5/8/11 5/9/11
1680 12/1/10 1/18/11
2369 8/9/10 10/1/10
2369 10/15/10 11/4/10

I've read some forums that suggested doing a min/max feature, but not quite sure how to use.

Any help would be appreciated.

Thank you