Area of the smaller rectangle = \(x(x+5)\)
Area of the larger rectangle = \(4x(x^2+7x+10) = 4x(x+2)(x+5)\)
Ratio of areas (smaller to larger) = \[\frac{x(x+5)}{4x(x+2)(x+5)} = \frac{x}{4x(x+2)} = \frac{1}{4(x+2)}\]
@Luigi0210 was taking the ratio of the sides of the small rectangle and comparing it to the ratio of the sides of the large rectangle, which is not what problem asks....that would be the right setup for determining if the rectangles were proportional in shape, however.
Gotta watch out, multiple-choice questions often have wrong answers that represent results you could get if you set up the problem incorrectly. Don't assume the answer is right just because it is one of the choices :-)