(a) Find two quadruples of positive integers (a, b, c, n), each with a different value of n greater than 3, such that \frac{a}{b}+\frac{b}{c}+\frac{c}{a}=n
(b) Show that if a, b, c are nonzero integers such that \frac{a}{b}+\frac{b}{c}+\frac{c}{a} is an integer, then a b c is a perfect cube. (A perfect cube is a number of the form n^{3}, where n is an integer.)