Go in Report Menu--Record Sort Expert -- and add Datetime field to it and change the order to Descending. so, you get latest record on top in each group.

 

In your report we have already created a formula @disp, using this formula you have to suppres the records.

 

Go In Seciton Expert--Select Detail section--Suppress Formula editor and give the following :

 

Whileprintingrecords;

numbervar x;

if x>10 then true else false