Răspuns :
prima e prin reducere, a doua prin sibstutie. La a doua scrii in loc de 3x+10y, 3x+9y+y
![Vezi imaginea Theexplorer](https://ro-static.z-dn.net/files/d53/a5e5ee397b8d7368761431e172f228c1.jpg)
Stiu doar prin metoda reducerii
3x+10y= 18/(-1)
3x+.9y=12si -3x-10y=-18
-1y= -6
y=-6/-1
y=6
3x+9y=12
3x+9*6=12
3x+54=12
3x=54-12
3x=42
x=42/3
x=14
3x+10y= 18/(-1)
3x+.9y=12si -3x-10y=-18
-1y= -6
y=-6/-1
y=6
3x+9y=12
3x+9*6=12
3x+54=12
3x=54-12
3x=42
x=42/3
x=14