Question 1089770
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The first department can select these two by 9*8 ways (any of 9 candidate to the first post; any of the 8 remaining to the second post).


The second department can select its representatives by 10*9 ways (following the same logic).


Third department has 8*7 ways.


In total, there are (9*8) * (10*9) * (8*7)  ways,


and I leave it to you to make final calculations.



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