Question

What is the solution to this system of linear equations: y-x=4 and y+2x=1

Answer 1

 -x + y = 4
2x + y = 1
    -3x = 3
     -3    -3
       x = -1
   -x + y = 4
-(-1) + y = 4
     1 + y = 4
  - 1         - 1
           y = 3
(x, y) = (-1, 3)