Răspuns :
[tex]\frac{7}{19}< \frac{x}{19}<\frac{13}{19} \\ \\ 7 < x<13 \\ \\ x \ apartine \ N \\ \\ \boxed{x=(8;9;10;11;12)}[/tex]
[tex]\frac{7}{19} < \frac{x}{19} < \frac{13}{19} \\
7<x<13\\
x\in\{8,9,10,11,12\}\\
cardinal(A)=5[/tex]
7<x<13\\
x\in\{8,9,10,11,12\}\\
cardinal(A)=5[/tex]