Question

2 X + Y is equal to 3 and X + 2 Y is equal to zero

Answer 1

2x+y = 3
x+2y = 0
2x+y = 3
2x+4y = 0 
3y = -3
y = -1 
x = 2

Answer 2

2x+y=3
x+2y=0
x=-2y
by substitution x=-2y in 2x+y=3 we get
2(-2y)+y=3
-4y+y=3
-3y=3
y=-3/3=-1
x=-2(-1)=2
thus x=2 and y=-1