Y=-4x because all you have to do is move the variable to the right by adding its opposite to both sides. So 4x+y-4x=0-4x. Then eliminate the opposites y=0-4x
Lets say that the length of a rectangle is 12 cm and the width is 5 cm, you would add 12+12+5+5 (as in the length on both length sides and the width on both sides) so the perimeter of this rectangle is: 34 cm
