Question 295620
Four girls and eight boys want to be president or vice president of the Student Council. 
A)  Out of 8 boys 2 can be selected in 8C2 = (8*7)/(1*2)=28 ways

B) Out of 4 girls 2 can be selected in 4C2 = (4*3)/(1*2)= 6 ways

C) Out of 8 boys 1 can be selected as president in 8C1 = 8 ways and

 out of 4 girls 1 can be selected as vice president in 4C1 = 4 ways.

Total number of ways = 8*4 = 32

D) Out of 8 boys 1 can be selected as vice president in 8C1 = 8 ways and

 out of 4 girls 1 can be selected as president in 4C1 = 4 ways.

Total number of ways = 4*8 = 32