a)

$\{\begin{array}{l}x+3y=2\mid \cdot 2\\ 3x-6y=-9\end{array}$  

 

$+\{\begin{array}{l}2x+6y=4\\ 3x-6y=-9\end{array}$  

$\underline{}$  

$2x+6y+3x-6y=4-9$  

 

$5x=-5\mid :5$  

 

$x=-1$       

 

$\{\begin{array}{l}x=-1\\ 3\cdot \left(-1\right)-6y=-9\end{array}$  

 

$\{\begin{array}{l}x=-1\\ -3-6y=-9\end{array}$  

 

$\{\begin{array}{l}x=-1\\ -6y=-6\mid :\left(-6\right)\end{array}$  

 

$\{\begin{array}{l}x=-1\\ y=1\end{array}$   

 

 

b)

$\{\begin{array}{l}5x-4y=2\\ 3x+2y=1\mid \cdot 2\end{array}$  

 

$+\{\begin{array}{l}5x-4y=2\\ 6x+4y=2\end{array}$  

$\underline{}$  

$5x-4y+6x+4y=2+2$  

 

$11x=4\mid :11$  

 

$x=\frac{4}{11}$          

 

 

$\{\begin{array}{l}x=\frac{4}{11}\\ 3\cdot \frac{4}{11}+2y=1\end{array}$  

 

$\{\begin{array}{l}x=\frac{4}{11}\\ \frac{12}{11}+2y=1\end{array}$  

 

$\{\begin{array}{l}x=\frac{4}{11}\\ 2y=-\frac{1}{11}\mid \cdot \frac{1}{2}\end{array}$  

 

$\{\begin{array}{l}x=\frac{4}{11}\\ y=-\frac{1}{22}\end{array}$