Answer:
a. 5 + 4 + 3 = 12
P(n,r) = P(12,12)
= 12!/(12−12)!
= 4.790016E+8
= 479,001,600
479,001,600/(5!4!3!) = 27,720 ways
b. 5! x 4! x 3! x 3! = 103,680
103,680/(5!4!3!) = 6 ways
c. 5! x 4! x 3! = 1 way
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