A developer has the job of building a new community of neighborhoods and businesses within a large plot of land. The regulations in this area require that a greenbelt of forrest must surround any new community on two adjacent sides. The greenbelt must have a uniform width and must have 10 times the area of the community. If the developer plans to make his community 3 kilometers wide and 4 kilometers long, how wide must the surrounding greenbelt be?

Question

anonymous · Answer

attachment

anonymous · Answer

From the text we can derive two Equations

Area Greenbelt = (x+4)(x+3) - 4*3

Area Greenbelt = 10(Area Community) = 120

Make them equal to eachother:

(x+4)(x+3) - 12 = 120

expand solve for x.

let me know if you have questions ^_^

anonymous · Answer

First equation derived from picture, not from text

anonymous · Answer

I got 8, -15

anonymous · Answer

But how do I know which answer is the width?

anonymous · Answer

only one of them makes sense.

width cannot be negative. that's how you know in this problem :)

anonymous · Answer

oh duh lol i guess i shoulda thought about it more

anonymous · Answer

thank you!