A box is to be constructed with a rectangular base and a height of 5 cm. If the rectangular base must have a perimeter of 28 cm, which quadratic equation best models the volume of the box?

V = lwh
P = 2(l + w)
y = 5(28 – x)(x)
y = 5(28 – 2x)(x)
y = 5(14 – x)(x)
y = 5(14 – 2x)(x)