Excel inventory control

[hecmar]

Hi

As per the attached. I cannot get there, what I am asking is that in sheet 1 there is a list of items, but in sheets 2 and 3 there maybe multiple of the same items. I need to count the items marked as "inventory" only as a number from sheets 2 and 3 onto sheet 1 corresponding with that particular item. Hope I make sense as its my first time here.

Thanks in advance