Question

At a park, a landscaper wishes to plant a uniform border of tulips around the outside of a 18m by 12m rectangular garden. The garden will look best if the area of the tulip border is half the area of the garden. How wide should the border be?

Answer 1

P=2(18)+ 2(12)= 36 +24+ 60
A+18x12=216
Tulip border= 216/2=108

(18+x)(12+x)=(18x12)/2 +216
216+18x+12x+x^2=108+216
x^2+30x-108=0
cannot factor
quadratic equation = -40.82 or -20.82

Answer 2

Guidance as to where I am going wrong?