The sum of the widths is $\displaystyle 2w$and since the width is half the length, each length is $\displaystyle 2w$. Since there are 2 lengths we get a total perimeter of $\displaystyle 6w$.

The best way to see that 750 feet of fence are needed is to look at this augmented diagram.

Note that two of the sides are extended to form a smaller rectangle whose sides can be deduced by subtraction. Since opposite sides of a rectangle are congruent, this allows us to fill in the two missing sidelengths of the original figure.

Now add: $\displaystyle 150+110+70+115+80+225 = 750 \textrm{ft}$

The perimeter of a rectangle is the sum of the length and the width, multiplied by 2:

$\displaystyle 2 (12.6 + 6.4) = 2 \cdot 19 = 38$

The rectangle has a perimeter of 38 centimeters.

The perimeter of a rectangle can be calculated by multiplying two by the sum of the length and width of the rectangle.

$\displaystyle 2\left ( 7 \frac{1}{2} +5 \frac{3}{5} \right )$

$\displaystyle =2 \left (\frac{7 \cdot 2 + 1}{2} + \frac{5\cdot 5 + 3}{5} \right )$

$\displaystyle = 2 \left (\frac{15}{2} + \frac{28}{5} \right )$

$\displaystyle = 2 \left (\frac{15 \times 5}{2 \times 5} + \frac{2 \times28}{2 \times5} \right )$

$\displaystyle = 2 \left (\frac{75}{10} + \frac{56}{10} \right ) = \frac{2}{1} \cdot \frac{131}{10} = \frac{131}{5} = 26 \frac{1}{5}$

The perimeter of the rectangle is $\displaystyle 26 \frac{1}{5}$ inches.

Since opposite sides of a rectangle have the same measure, the missing sidelengths can be calculated as in the diagram below:

The sidelengths of the green polygon can now be added to find the perimeter:

$\displaystyle P= 35 +60 + 35 + 15 + 20 + 30 + 20 + 15 = 230$

The perimeter of a rectangle is the sum of its sides.

The sum of the widths is $\displaystyle 2w$ and since the width is one-third of the length, each length is $\displaystyle 3w$. Since there are $\displaystyle 2$ lengths we get a total of $\displaystyle 6w$. Widths + lengths = $\displaystyle 2w + 6w = 8w$

$\displaystyle \Delta ABC$ is equilateral, so $\displaystyle AC = AB = 25$.

Also, since opposite sides of a rectangle are congruent, 

$\displaystyle DE = AC = 25$ and $\displaystyle AE = CD = 40$

The perimeter of Rectangle $\displaystyle ACDE$ is 

$\displaystyle AC + CD +DE + AE = 25 + 40 + 25 + 40 = 130$

150 hectares is equal to $\displaystyle 150 \times 10,000 = 1,500,000$ square meters.

The width of this land is 1.2 kilometers, or $\displaystyle 1.2 \times 1,000 =1,200$ meters. Divide the area by the width to get:

$\displaystyle 1,500,000 \div 1,200 = 1,250$ meters

The perimeter of the land is 

$\displaystyle 2 \left ( 1,200 + 1,250\right ) = 4,900$ meters, or $\displaystyle 4,900 \div 1,000 = 4.9$ kilometers.

$\displaystyle l=2w=2(4)=8$

$\displaystyle P=l+w+l+w=2l+2w=2(8)+2(4)=16+8=24$

The perimeter of a rectangle is simply the sum of the four sides:

$\displaystyle 1000+1000+100+100=2200\; meters$