This is a combination problem, since the order does not matter.
4 men chosen from 5 men = 5 C 4 = 5! / (4!x1!) = 120 / 24 = 5
3 women chosen from 6 women = 6 C 3 = 6! / (3!x3!) = 720 / (6x6) = 20
So, using multiplication rule,
total committees = 5 x 20 = 100 (final answer)