vlookup alternative to sum rows

[emilyf]

Hi!
I think this is a simple problem, but I've searched and I can't find the answer!
I have a list of codes with quantities against them. Some of the codes appear 2 or 3 times with different quantities against them.
On another worksheet I want to lookup against this list of codes and sum all quantities next to each occurence of that code. VLOOKUP doesn't work because it only returns the value of the first occurrence. I'm thinking maybe index match but am not sure how to use that.
Can you help? I've attached a basic version of the worksheet...
Thanks!