Question

What is the solution to the system of equations for y= -2x - 4 and y= 2x + 4

Answer 1

Y = -2x - 4

y = 2x +4

add the two equation

2y = 0 , y =0

2x + 4 = 0

2x = -4

x = -2

Answer 2

Y = -2x - 4
y = 2x + 4

substitute the first equation into the second equation to find x;
-2x - 4 = 2x + 4
-4 = 2x + 4 + 2x 
-4 = 4x + 4
-4 - 4 = 4x
-8 = 4x
-2 = x

solve for y given the value of x into the first equation;
y = -2x - 4
y = -2(-2) - 4
y = 0

the answer is; 
x = -2, y = 0     or (-2, 0)

hope this helps, God bless!