The number of permutations of the 26 letters of the English alphabet that do not contain any of the strings fish, rat, or bird is 402619359782336797900800000
Let

Then

Note that since
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But since
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and
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Since

where 
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What we are looking for is the number of permutations of the 26 letters of the alphabet that do not contain the strings fish, rat or bird, or

This link contains another solved problem on permutations:
brainly.com/question/7951365
The answer is 5.477225575.... or 5.5 if you want the simplified ansewer
The decimal that is equal to 2/3 is...
0.66666666666
Hope this helps

Multiply 4.8 into (20/3), and multiply 16/9 with (1.2b)

Multiply 9 on both sides
19.2b = 32(9)
19.2b = 288 Divide 19.2 on both sides
b = 15