System of Linear Equations entered :
[1] x - y = 4
[2] x + y = 9
Graphic Representation of the Equations :
y + x = 4 y + x = 9
Solve by Substitution :
// Solve equation [2] for the variable y
[2] y = -x + 9
// Plug this in for variable y in equation [1]
[1] x - (-x +9) = 4
[1] 2x = 13
// Solve equation [1] for the variable x
[1] 2x = 13
[1] x = 13/2
// By now we know this much :
x = 13/2 y = -x+9
// Use the x value to solve for y
y = -(13/2)+9 = 5/2
Solution :
{x,y} = {13/2,5/2}
Hope it Helps ☺