Решите систему х-у=3 2х+2у=4

[latex] \left \{ {{x-y=3} \atop {2(x+y)=4}} \right. \left \{ {{x=y+3} \atop {y+3+y=2}} \right. \left \{ {{x=y+3} \atop {2y=-1}} \right. \left \{ {{x=y+3} \atop {y=-\frac{1}{2} }} \right. \left \{ {{x=y+3} \atop {y= -\frac{1}{2} }} \right. \left \{ {{x=3- \frac{1}{2} } \atop {y=- \frac{1}{2} }} \right. \left \{ {{x= \frac{5}{2} } \atop {y=- \frac{1}{2} }} \right. [/latex]

X=3+y 2(3+y)+2y=4 6+2y+2y=4 2=-4y y=-0,5