I would assume that if you've already posted something like this, you should be able to answer this question on your own.
to get a max date:to subtract a max date from the previous date, it's too tough with the query builder alone. You need code:
Code:
set rs = db.openrecordset("select top 2 * from table order by [datefield] desc")
rs.movelast
variable = rs!value
rs.moveprevious
variable2 = rs!value
result = variable2 - variable
Again, it is possible with the query builder, but the specs of your problem are not clear, but the idea to solve the problem is certainly there.