The Double Pyramid

$\quad \quad \quad \quad A\\ \quad \quad \quad B\quad C\\ \quad \quad D\quad E\quad F\\ \quad G\quad H\quad I\quad J\\ K\quad L\quad M\quad N\;\; O\\ \quad P\quad Q\quad R\quad S\\ \quad \quad T\quad U\quad V\\ \quad \quad \quad W\;\: X\\ \quad \quad \quad \quad Y$

In the above pyramid, every letter is the sum of the two letters below it. If the letter only has one letter below it, the letter is the value of that letter. For example,

G = K + L

W = Y because Y is the only letter below W.

What is the value of $\frac{A}{Y}$ ? Assume that Y > 0.