If relation is only Date then try this query, it should work
With X (Date1,Amount)
AS
(
Select CONVERT(varchar,Date,105),Amount as Date1 from table_2
),
Y (Date1,Amount)
AS
(
Select CONVERT(varchar,Date,105),Amount as Date1 from table_3
)
select SUM (X.Amount) + SUM (X.Amount),X.Date1 as 's' from X
inner Join Y ON X.Date1=Y.Date1
Group BY X.Date1