Calculation question

[gerrycastellino]

Hello:

Trying to get this calculation in a table.

So the ETE% is a division  of Count of product a  by total count of All products for the Salesrep + added

common products for other salesreps.

So for example, the first line would be:

10 / (10 + 10 + 10 + 20 + 20) = 14%.

How do I count all the products for a Salesrep + add sales of common products to Salesrep James.

Salesrep	Product	Qty Sold	ETE%
James	A	10	14%
James	B	10	14%
James	C	10	14%
John	A	20	29%
John	B	20	29%
John	D	20	100%