Answer:
(a) 350
(b) 175
(c) 21
(d) 196
Step-by-step explanation:
Number of females = 7
Number of males = 5
Total ways of selecting r items from n items is

(a)
Total ways of selecting 3 females and 2 males.




(b)
Total ways of selecting 4 females and 1 male.



(c)
Total ways of selecting 5 females.



(d)
Total ways of selecting at least 4 females.
Total ways = 4 females + 5 females


Step-by-step explanation:
Let the number be x, then

You would divide it into shapes that you already know, like squares, rectangles and triangles. Find the area of each shape and add them together