Compare Worksheets return third result

I Have two worksheets
a) Warehouses Combined - this list all codes a to z
b) Suppliers - list all suppliers with discount per supplier.

Warehouse Combined - column H:H list Supplier Codes against each Stock Code Supplier Code appears multiple times against stock codes.
Suppliers - A:A list all suppliers individually and G:G has the discount against each Supplier.

1) I want to compare H:H against list A:A and return % Value G:G to Warehouses Combined in new column.
2) I want to compare H:H against list in A:A and subtract % discount against Value that is in Warehouse Combined

Warehouse Combined
a) H:H Supplier Codes
b) O:O Value based on quantity x Stock on Hand
c) P:P New Column should copy % Discount into this Column
d) Q:Q Value Less Set Discount compare Supplier codes and calculate value less discount

Suppliers (Worksheet)
a) A:A List of Individual Supplier codes
b) G:G % discount per supplier in A:A