garden that is 10 feet by 20 feet is surrounded by a walkway of uniform width. The area of the garden and walkway together is 600 square feet. Find the width of the walkway.

Let x be the width of walk way.

THe dimensions of whole rectangle including walk way are (10+2x), (20+2x).

(10+2x)*(20+2x)=600.

200+20x+40x+4x^2=600.

4x^2+60x+200-600=0.

4x^2+60x-400=0.

x^2+15x-100=0.

(x+20)(x-5)=0.

x=-20 or 5.

Ignore -20.

Width of wlak way =x= 5 ft.