this is a real simple question if you think about it, but while i was oing the ther permutation questions, i cant seem to pull of an answer to this.. can anyone help me out? thank you

five cards bearing the numbers 3,5,6,7, and 8 are given

a) how many numbers greater than 5000 can be formed??

b)how many even numbers greater than 50000 be formed?

c)how many odd numbers less than 400 can be formed?