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Consider all possible permutations of eight distinct elements $a, b, c, d, e, f, g, h$. In how many of them, will $d$ appear before $b$? Note that $d$ and $b$ may not necessarily be consecutive.
in Combinatory by Veteran (106k points)
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2 Answers

+2 votes
8!/2! as (d,b) is the only permitted arrangement between d and b , so it is equivalent to treating them as similar objects.
by Junior (623 points)
0
d,b is not the only arrangement. d,a,c,b is also permitted. consecutive not necessary
0 votes

d should be placed before b.
answer in pic (courtesy: friend) 

by Active (3.8k points)

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