## Task 1 - 120721

Determine the pairs $(x, y)$ of natural numbers $x$ and $y$ for which the following conditions hold:

(1) The sum of the two numbers $x$ and $y$ is 15390.

(2) If the single-digit number $x$ is placed in front of the number $y$, the resulting number $z$ is four times as large as the number $u$ obtained by placing the number $x$ behind the number $y$.