If each digit in the set of A = (2,3,4,5) is exactly used once, in how many ways can the digits be arranged such that the 3 and 4 are not adjacent?  Pick:
A) 12	B) 15	C) 18	D) 22	E) 24
The answer should be = total arrangements - arrangements when 2 and 5 are together.   = 4! - 3! * 2! = 24 -12= 
<gadget id="calculator">24 -12</gadget>
<output>12</output>
12   take 2,5,(3,4) here there are 3 entities whose number of arrangements are 3! and 2! is the arrangement between 3 and 4   12nswer is 12
<result>A</result>
If each digit in the set of A = (2,3,4,5) is exactly used once, in how many ways can the digits be arranged such that the 3 and 4 are not adjacent?