Question 388802
# ways of choosing 1 man from 5 = 5C1 = 5.
# ways of choosing 1 woman from 4 = 4C1 = 4.
# ways of choosing 2 people from 7 remaining people = 7C2 = 21.
By the fundamental principle of counting, the #ways of choosing 4 people so as to include at least 1 man and 1 woman is 5*4*21 = 420.