The answer to this system of equations is: Â " x = 1 " ; Â y = - 8" ;Â
                          or; write as:  " [1, - 8] " .
Explanation:
Given the system of equations:
y = -9x + 1 Â ;Â
y = -4x − 4 ;
Solve for "x" ; and "y" ;Â
Â
→  y = y ; ↔
→  - 4x − 4  =  - 9x + 1  ;
Add  "4x" to each side of the equation; & add "4" to each side of the equation:
→  -4x − 4 + 4x + 4  =  -9x + 1 + 4x + 4  ;Â
to get:
→  0  =  -5x + 5 ;Â
↔  -5x + 5 = 0  ;
Subtract "5" from each side of the equation:
→  -5x + 5 − 5 = 0 − 5 ;Â
to get:Â
→  -5x = -5 ;Â
Divide each side of the equation by "-5" ;
   to isolate "x" on one side of the equation; & to solve for "x" ;
→  -5x /-5 = -5 / -5 ;Â
to get:
 →  x = 1  ;
Now, plug in "1 " for "x" ; in  either of the 2 (two) equations given;
      to solve for "y" ;
Let us try the first equation given:
  →  " y = - 9x + 1 " ;
   →  " y = - 9(1) + 1 ;
         =  - 9 + 1  = - 8 .Â
   →  y =  - 8 .
To check our
Now, let us try substituting "Â 1Â " for "x" ; in the second equation;
    to see if we get the same value for "y";  that is; " y = - 8 "  ;Â
   →  "  y =  - 4x − 4 "  ;Â
       y =  - 4(1) + 4 ;
       y =  -  4 − 4 = - 8 .
    →  y = - 8 .
The answer to this system of equations is: Â "Â x = 1 " ; Â y = - 8 " ;Â
                          or; write as:  " [1, - 8] "  .Â