# The Perimeter of a Rectangular pig pen is 210Ft. The length is 5ft greater then the width. How do you find the Length?

Mar 13, 2016

Length = 55 ft

#### Explanation:

Let length be $L$
Let width be $W$

Perimeter$= 2 W + 2 L = 210$ ...............................(1)

But we are told that L=W+5" .........................(2)

So, as we need to find length we need to 'get rid' of $W$
Rearranging equation (2) we gave:

$W = L - 5$

Substitute for W in equation (1) gives

$\text{ } 2 \left(L - 5\right) + 2 L = 210. \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots . \left({1}_{a}\right)$

Multiply out the bracket

$\text{ } 2 L - 10 + 2 L = 210$

$\text{ } 2 L + 0 + 2 L = 220$
$\text{ } 4 L = 220$
$\text{ } L = \frac{220}{4} = 55$