How do you solve the linear system

Question

Estimate the solution? x+y=-7 , 2x+y= -11

Answer 1

The system of equations are 

x + y  =  - 7 ----------------> (1)

2x + y  =  - 11 -----------------> (2)

Subtract Eq (1) from Eq (2)

       2x + y  =  - 11

         x + y  =  - 7

      (-)   (-)      (+)

   ---------------------------

              x  =  - 4

Substiute x = - 4 in Eq (1)

-4 + x  =  - 7

x  =  -7 + 4

y  =  - 3

Answer :

The solutions are x = - 4  and  y = - 3.