1.28 If $\frac{y}{x-z}=\frac{x+y}{z}=\frac{x}{y}$, where $x, y, z$ are three different positive numbers, then $\frac{x}{y}$ equals
(A) $\frac{1}{2}$.
(B) $\frac{3}{5}$.
(C) $\frac{2}{3}$.
(D) $\frac{5}{3}$.
(E) 2 .
(43rd American High School Mathematics Examination, 1992)
［Solution］ By the property of proportional division and the given conditions, we have
$$
\frac{x}{y}=\frac{y+(x+y)+x}{(x-z)+z+y}=\frac{2(x+y)}{x+y}=2 .
$$

Therefore, the correct choice is $(E)$.