Question

x+y = 2x - y ou 4x - 2y = a

Answer 1

y y=2x-y-x
y= x-y
x=-y-y
x=-2y. substituindo teremos
x+y=2x-y
-2y+y=2.-2y-y
-y=-4y-2y
-y=-6y
-6y+y=
-5y
-y=5(-1)
y=-5
logo
x+y=2x-y
x+(-5)=2x-(-5)
x-5= 2x+5
x-2x=0
x=-1