Question 295047
They are both equal to y.
Set them equal to each other.
2x+3=-x-4
3x=-7
x=-7/3
y=7/3-4
y=7/3-12/3
y=-5/3
or we could
y=2x+3 and 
y=-x-4
subtract the second from the first
0=3x+7
-7=3x
-7/3=x
That looks familiar.