Counting items
 

How would i count the number of times that two items are listed together in
the same row in a string of cells say b2 to g12. "sell" and "stock" are
togeter in rows D, E and F. Say - "Sell" is D3 and "stock" is D11, "sell" is
E5 and "stock" is E7, "sell" is F2 and "stock" is F8. What fomula could i
use that would give me an answer of 3?
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thanx