The perimeter of rectangle ABCD is 42 cm and the area is 80 cm2. Which equation can be used to find the dimensions of the rectangle? (Hint: Set up a system of equations).

xy + 2x + 2y = (42)(80)
x^2 + 80x - 42 = 0
x^2 - 42x + 80 = 0
x^2 - 21x + 80 = 0