permutaions or combinations problems help please!!!!!!!!!!!!

1) In how many ways can 5 seats on a bench be assigned from amongst 12 people?

2)John and Harry Invited four other people to sit on their bench. In how many ways can these six people be seated on this bench if:
a)there are no restrictions
b)john is seated at the left end and Harry is seated at the right end
c)John and Harry must be seated together.

3)You bought five house numbers at your lumber supply store. The numbers are 1,2,3,4 and 5.How many three-digit house numbers a)are even? b)are possible?

4) Solve:
a) nC2=10
b)nC3 = 3(nP2)

2)John and Harry Invited four other people to sit on their bench. In how many ways can these six people be seated on this bench if:

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a)there are no restrictions

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We can arrange 6 people in 6!=720 ways.

b)john is seated at the left end and Harry is seated at the right end

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Seat John and Harry in their assigned places. Then, arrange the other 4 people.

c)John and Harry must be seated together.

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Tie John and Harry together and pretend they are one person. They can be tied together in 2 different ways and the whole lot can be arranged in 5! ways.

hey galactus I have some more qiestions to ask can I go ahead?

Please post new questions as a new thread. Please show your work and reasoning so far, so the helpers can "see" where you are stuck.

Thank you!