3. Solve the equation in natural numbers: $\frac{1}{x}+\frac{1}{y}=\frac{1}{4}$. In the answer, list all possible values of the number $x$ in ascending or descending order, separated by commas or semicolons.
Answer: $5,8,20\|5 ; 8 ; 20\| 20,8,5 \| 20 ; 8 ; 5$

## Examples of answer notation: $1 ; 2$  $1,2,3$

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