If a, b, and c are positive integers such that a is divisible by b, and c is divisible by a, which of the following is NOT necessarily an integer?  Choose the correct choice from the following choices.
A) (a + c)/b
B) (c - a)/b
C) ca/b
D) (c + b)/a
E) cb/a
a=bx.........(1)   c=aY.........(2)   a. (A+C)/B = (bx+ay)/b = (bx+ bxy)/b =x+xy=integer   b. (c-a)/b = (ay-a)/b = a(y-1)/b = bx(y-1)/b = integer.   similarly   All options were integer except D.   d.(c+b)/a   ay+b)/a .....not integer......   Ans (c + b)/a
<result>D</result>
If a, b, and c are positive integers such that a is divisible by b, and c is divisible by a, which of the following is NOT necessarily an integer?