1. Solve the linear system using substitution.
4x-y=5
4x+4y=-4
substitute y=4x-5 into 4x+4y=-4 to get
4x+4(4x-5) = -4
4x+16x-20 = -4
20x = 16
x = 4/5
so, y = -9/5
4x-y=5
4x+4y=-4
4x+4(4x-5) = -4
4x+16x-20 = -4
20x = 16
x = 4/5
so, y = -9/5