Question

Consider the following pair of equations:

Answer 1

 {  y = x + 4
    y = - 2 x - 2 

Subsititute  y = - 2 x - 2 :

[ (- 2 x - 2 ) = x + 4 ]

( - 2 x - 2 ) = x + 4

Add 2 to both sides:

- 2 x - 2 + 2 = x +  4 + 2

- 2 x  = x + 6 

Subtract x for