Question

Vijay is building a new rectangular enclosure in his backyard for his chickens. He has 40 feet of fencing material and he wants the width of the enclosure to be 8 feet. If l is the length of the enclosure, and Vijay used all of the fencing material, which equation best models the situation?

A. l + 8 = 40

B. 2l + 8 = 40

C. 2(l + 8) = 40

D. 2l + 2(l + 8) = 40

Answer 1

C

Explanation:

Since all of the fencing material is used, then an equation that could model this situation is l + l + 8 + 8 = 40l+l+8+8=40l, plus, l, plus, 8, plus, 8, equals, 40.

Hint #3

By collecting like terms, our equation is now 2l + 16 = 402l+16=402, l, plus, 16, equals, 40. Since this is not an answer choice, let's see if we can write this another way. By factoring 222, we obtain:

\qquad2\left(l+8\right)=402(l+8)=402, left parenthesis, l, plus, 8, right parenthesis, equals, 40

Hint #4

The correct answer is:

\qquad 2\left(l+8\right)=402(l+8)=40

Answer 2

The answer is C

The reason: There are two width and two length sides. So, therefore, if you want the fencing to equal 40 feet around the perimeter, 8 · 2 + L · 2 has to = 40.
You would factor 2 out, and you get 2(8 + L) = 40.