Small List Of How Do I's

Consider a recordset consisting of
Vendor, Invoice, InvAmt, Item,ItemAmt
1, 'A12345', 100.00,'Item1', 25.00
1, 'A12345', 100.00,'Item2', 50.00
1, 'Z22222', 200.00,'Item1',100.00

1, 'Z22222', 200.00,'Item3', 50.00
2, 'A12345', 300.00,'Item4,' 250.00

I have a report that groups by vendor and then by invoice within a vendor.

I want to create a report totals that contains

Number of vendors=2
Number of invoices=3
Total Inv Amounts=600.00
Total Item Amounts=475.00


How?
Number of vendors is =count(distinct vendors) ??
Cant do that for # Invoices because of possible duplicate invoices used by different vendors.
How do i get the total invamt? Each occurrence of the invamt fld is in a list2 as =first(invamt).
I really need the sum of each first(invamt).

Thanx Up Front.
Jerry C