Решите систему х-у=3 2х+2у=4

Решите задачу:

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