Răspuns:
x=45/8,y=35/8
Explicație pas cu pas:
-2x+6y=15
2x+2y=20
-2x=15-6y
x=(15-6y)/(-2)
2*(15-6y)/(-2)+2y=20
-15+6y+2y=20
8y=35
y=35/8
x=(15-35/8)/(-2)
x=-(120-35)/16
x=90/16
x=45/8