Cross worksheet average sales of unique products

[Kalemaroni]

Worksheet1

Product	Transaction ID	Unique Product Name	Average Sales of Unique Product Name
A	B	C	D
Apples	1	Apples	=???
Apples	2	Carrots	=???
Onions	3	Onions	=???
Carrots	4

Worksheet2

Transaction ID	Sales
A	B
1	10
2	20
3	10
4	10

I'm looking for a formula that will display the Average Sales of the Unique Product Names listed in Column C of Worksheet1 into column D of Worksheet1. Expected value of Worksheet1!D1 is 15 and Worksheet1!D2 and D3 are 10

 

[Kalemaroni]

Just to clarify, there are 2 worksheets. The Transaction ID column in each can be used to link the Sales in Worksheet2 to the products that were sold in column A of worksheet1. Column C contains a formula that generates the cells from the unique cells of column A.