finding tuples

Question

Comments

But answer is 800 given

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Answer given is correct..

Do consider the primary key factor while calculating.

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can you explain

Answer 1

Multipliy each  of the table's tuple.The above is an inner join which is ultimately a form of cartesian product. Yeah!!!.
 

100X50X80X10=4000000. So this is d answer. Coz as u can see this is d cross product of all d tuples simply put together. I hope it helps you. :)