,

Add to both sides of the equation.

Replace all occurrences of in with .

Simplify .

Simplify each term.

Apply the distributive property.

Multiply by .

Multiply by .

Combine the opposite terms in .

Add and .

Add and .

Remove any equations from the system that are always true.

Solve by Substitution -x+4y=4 , x-4y=-4