Odpowiedź:
[tex]\left \{ {{1/2(x-y)=1/3(x+y)} \atop {4/5x-1/5(y+3x)=-4}} \right.\\\left \{ {{1/2x-1/2y=1/3x+1/3y} \atop {4/5x-1/5y+3/5x=-4}} \right. \\\left \{ {{3/6x-3/6y=2/6x+2/6y} /*6 \atop {4/5x-1/5y+3/5x=-4}} \right. \\ \left \{ {{1/6x-1/6y=0} /*6 \atop {7/5x-1/5y=-4} /*5} \right.\\\left \{ {{x-y=0} \atop {7x-y=-20}} \right. \\x=y\\7y-y=-20\\6y=-20\\y=-20/6=-10/3\\\left \{ {{y=-10/3} \atop {x=-10/3}} \right.[/tex]
