n/m means that n is factor of m, then the relation f is

n/m means that n is a factor of m. So, f is reflexive. A number is a factor of itself. Now, if n is a factor of m, then m is not a factor of n ∴f is not symmetric. Let n is a factor of m and m is a factor of s, then it is true that n is a factor of s. ∴f is transitive.