In the lesson, the number of all-boy four-person committees on the Central High student council was calculated as C(8,4)=70, the number of all-girl four-person committees was calculated as C(9,4)=126, and the number of four-person committees that are half boys & 1/2 girls are calculated as C(8,2) × C(9,2) = 1008.
a. How many four-person committees consist of three girls and one boy?