$a\text{)}\{\begin{array}{l}-\frac{1}{3}x+y=2\mid \cdot 3\\ x+y=2\end{array}$  

$\left(+\right)\{\begin{array}{l}-x+3y=6\\ x+y=2\end{array}$  

$\underline{}$  

$4y=8$  

$y=2$  

zatem: