A fraternity name formed by two letters would have 24 choices for the first letter, and 24 choices for the second, therefore 24*24=576 is the correct answer.
-2/9 x 4/9 is -8
so the answer is -2/9
It was would numbers 000-000-0000 through 999-999-9999. So that would be 9,999,999,999 + 1 = 10 billion different 10-digit phone numbers.
45 min. - 4 peoples - 5 walls
? min. - 6 peoples - 4 walls
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180 min. - 1 man - 5 walls ⇒
36 min. - 1 man - 1 wall ⇒
6 min. - 6 peoples - 1 wall ⇒
24 min. - 6 peoples - 4 walls (answer)
