[tex] \left \{ {{9y+10x=21|\cdot 3} \atop {4y+6x=18|\cdot 5}} \right. \Leftrightarrow \left \{ {27y+30x=63} \atop {20y+30x=90}} \right.\\
Daca\ scadem\ relatiile: 7y/= -27\Rightarrow \boxed{y=-\frac{27}{7}}\\
4\cdot \left(-\dfrac{27}{7}}\right)+6x=18\\
-\dfrac{108}{7}+6x=18\\
6x=18+\dfrac{108}{7}\\
x=3+\dfrac{18}{7}\Rightarrow \boxed{x=\dfrac{39}{7}}[/tex]
