Arectangle has sides measuring (4x + 5) units and (3x + 10) units.
part a: what is the expression that represents the area of the rectangle? show your work to receive full credit.

part b: what are the degree and classification of the expression obtained in part a?

part c: how does part a demonstrate the closure property for polynomials?

i got a and b i just need with c
here is what i got for a and b

part a: area equals length times width
equals (4x + 5)(3x + 10) equals 12x^2 + 55x + 50

part b: the degree is 2, it's a quadratic expression.