6! means 6x5x4x3x2x1 . . . . .4! means 4x3x2x1
A. 6 x 5 x 4! / 4! x 2!
= 30 / 2
=15
B. 4 x 3!/ 2! 3!
= 4 / 2
= 2
C. i'm not sure what the dots means, is i assume its a minus
( 24 + 6) (6 - 2)
30 x 4 = 120
D. 120 - 24 = 96
So, the order will be B - A - D - C
hope this helps