Question 110434
30*40=1200 sqft for the garden area.
adding the walk way we have an area is:
(30+2x)(40+2x)=1800
1200+80x+60x+4x^2=1800
4x^2+140x+1200-1800=0
4x^2+140x-600=0
4(x^2+35x-150)=0
using the quadratic equation we get:
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
x=(-35+-sqrt[35^2-4*1*-150)/2*1
x=(-35+-sqrt[1225+600])/2
x=(-35+-sqrt1825)/2
x=(-35+-42.72)/2
x=(-35+42.72)/2
x=7.72/2
x=3.86 answer for the width of the walkway.