Question

How many solutions does this system of equations have?

x+y= -4

x -y= 0

Answer 1

x+y= -4
x -y= 0
Since slope = -a/b of the linear equation having general form ax +by+c =0
slope of equation 1 = -(1/1) = -1
slope of equation 2 = -(1/-1) = 1
Since their slope are not the same, they have a intercept.
(for more info. the lines are also perpendicular to each other as the product of their slope =-1)