Tha area of a triangle is 5x^3+19x2+6x-18 with length x+3. Using synthetic division,what is the width of the rectangle

A)5x^2+4x-6

B)5x^2+34x+108+306/x+3

C)5x^3+4x^2-6x

D)5x^2+34+108+306/x-3