He has 16 comedy movies, 12 scary movies and 8 action movies.
He can pack only one type of DVD in each box and he must pack the same number of DVDs in each box
So, we need to find the greatest common factor between 16 , 12 and 8
16 = 2 * 2 * 2 * 2
12 = 2 * 2 * * 3
8 = 2 * 2 * 2
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2 * 2 = 4
So,
The greatest number of DVDs Scooby can pack in each box = 2 * 2 = 4
The answer is option B. 4
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More explanations :
So, he will pack 16 comedy movies at 4 packs, each pack has 4 DVDs
And he will pack 12 scary movies at 3 packs, each pack has 4 DVDs
And he will pack 8 action movies at 2 packs, each pack has 4 DVDs
So, the total number of packs = 4 + 3 + 2 = 9 packs