Odpowiedź:
[tex]\left \{ {{x+y=3} \atop {x-y=27}} \right. \\\\\left \{ {{x=3-y} \atop {3-y-y=27}} \right. \\\\\left \{ {{x=3-y} \atop {3-2y=27}} \right. \\\\\left \{ {{x=3-y} \atop {-2y}=9\right. \\\\\left \{ {{x=3-y} \atop {y=-4,5}} \right. \\\\\\x=3-y\\x=3-(-4,5)\\x=7,5[/tex]
