I have a Range area which is dynamic and I wish to create a formula that
will add up values within this dynamic range if two conditions exist

Col A = Location
Col C = Product Number
Col E = Sales Units (of the products in Col C that have been sold in Col A -
location)

I only wish to add some of the products that are listed, not all. Therefore
is cell A1 on Sheet1 I want to create a formula that will do the following

Add up all quantities that are in Col E that relate to Product Number "43",
that are sold at Location - "London"

How can I do that?

Thanks