SSRS 2012: Find percentage between numbers from different datasets

Hi All ,

Deployed in SSRS 2012.

Scenario:

1st tablix - count (transactions) - dataset1
2nd tablix - count (transactions) - dataset2

Above data is for past week, so 7 rows per report

I need to find percent such that :

Day 1 -- (Dataset1.count (transactions) /Dataset2.count (transactions)) * 100

Day 2 -- (Dataset1.count (transactions) /Dataset2.count (transactions)) * 100
and so on...

I am aware of some Lookup function but it does not seem to work, below is what I did:

=Lookup(Fields!Dataset1.Value,Fields!Dataset2.Value,Fields!Dataset2.Value, "DataSet2")

As both datasets just return count, I think there is no column common in both and hence Lookup cannot be used?

In report layout, is there a way to create 3rd tablix and access data from the 2 datasets to calculate this percentage?

Need help urgently!!

Thanks in advance,
Mandar