Calculating Conversion Rate between Main/Subreport Data

Hope you can help with this. I have a main report that lists a number of packs sent out to categories in a period by a specific consultant:-

Category 1 57

Category 2 48

This is sorted in descending order with the highest number of packs sent first.

I have created a sub-report that contains information on deals confirmed by category by consultant and have managed to link the subreport to the main report by the date period, the appropriate consultant and the category name. The subreport is parallel to the category group footer that determines the counts shown above. This is working fine. My report now looks like the below:-

Category 1 57 5 £480.00

Category 2 48 1 £125.00

Where the third column is the number of deals confirmed for the category and the deal average value for those deals.

However, I need to show a total of the Deals Confirmed and the Total Average Value, I also need to show a conversion rate % in another column on the end i.e. 5 Confirmed Deals out of 57 Packs sent is a conversion rate of 8.77%.

Q1 How do I total up the sub-report figures onto the main report?

Q2 How do I should a conversionh rate based on a figure from the main report and a figure from the subreport?

Hope someone can assist with this.

Many Thanks