Please answer this as soon as possible.

kim has a garden which is 9 feet long and 20 feet wide. she wants to put a border around the garden which is the same width all around. what is the expression for the perimeter of the outside edge of the border?

A) 4x+58
B) 2x+29
C) 4x^2+58x+180
D) x^2 +29x+180