Agroup consists of fourfour men and eighteight women. threethree people are selected to attend a conference. a. in how many ways can three three people be selected from this group of twelve twelve

Take the combination of 1 man and 2 women
 =4 * 8C2 = 4*28 = 112 ways
The case of all men
= 4C3 = 4
The case of all women
= 8C3 = 56
The case of 2 men and 1 woman:-
= 8 * 4C2 =  8* 6 = 48

Total number of ways = 112 + 4 + 56 + 48 =  220 answer

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B. because the 7 represents "seven times", x represents "a number", 12 represents "plus twelve", and -4 represents "minus four"