Answer:
the right answer is : -3
Step-by-step explanation:
[tex]\left \{ {{x+y=4} \atop {3x+4y=14}} \right. \\\left \{ {{-3(x+y)=-3*4} \atop {3x+4y=14}} \right. \\\left \{ {{-3x-3y=-12} \atop {3x+4y=14}} \right. \\\left \{ {{-3x-3y+3x+4y=2} \atop {3x+4y=14}} \right. \\\left \{ {{-3y+4y=2} \atop {3x+4y=14}} \right. \\\left \{ {{y=2} \atop {3x+4*2=14}} \right. \\\left \{ {{y=2} \atop {3x=14-8=6}} \right. \\\left \{ {{y=2} \atop {x=\frac{6}{3}=2 }} \right.[/tex]
