Answer:
C
Step-by-step explanation:
1. The formula for calculate the perimeter of a rectangle, is:
P=2L+2W
P is the perimeter of the rectangle (P=320 feet).
L is the lenght of the rectangle.
W is the width of the rectangle.
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2. The problem says that the length of the rectangle is three times the width, so you have:
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L=3W
3. When you substitute L=3W and P=320, into P=2L+2W, you obtain:
P=2L+2W
320=2(3W)+2W
320=6W+2W
8W=320
W=320/8
W=40 feet
4. The barn forms one end of the rectangle. Therefore the linear feet of fence (x) is:
x=P-W
x=320 feet-40 feet
x=280 feet
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How many linear feet of fence must he buy?
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The answer is: 280 feet
Answer:

General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Algebra I</u>
<u>Algebra II</u>
- Distance Formula:

Step-by-step explanation:
<u>Step 1: Define</u>
<em>Identify</em>
Point (2, 1)
Point (6, 7)
<u>Step 2: Find distance </u><em><u>d</u></em>
Simply plug in the 2 coordinates into the distance formula to find distance <em>d</em>
- Substitute in points [Distance Formula]:

- [√Radical] (Parenthesis) Subtract:

- [√Radical] Evaluate exponents:

- [√Radical] Add:

- [√Radical] Simplify:

For this case we propose a rule of three:
foot ------------->
hour
x -----------------------------------> 1 hour
Where "x" represents the amount of foot in one hour.

So, we have
foot every hour.
Answer:
foot every hour