SUMPRODUCT using a condition

Hi,

I would like to create a formula in D7 that calculates the weighted average growth for products (column A) manufactured by Bob (column B). In J5 I’ve inserted the expected result using a SUMPRODUCT function.

Can someone please tell me how to create a formula in D7 that will calculate from the data in B6:D6 the same result as in J5. i.e. How do I make the SUMPRODUCT function only consider data in columns C and D when Bob is the manufacturer?

Thanks very much!