You install 580 feet of fencing along the perimeter of a rectangular yard. The width of the yard is 144 feet. What is the length of the yard?

Explanation:

The units for each are in feet.

The formula tying together all three variables is

P = 2(L+W)

which is the same as saying

P = 2L+2W

We can think of it having two copies of L and two copies of W, four sides total, added together to get the full perimeter.

I'll go with the first version. Plug in the given values and solve for L

P = 2(L+W)

2(L+W) = P

2(L+144) = 580

L+144 = 580/2

L+144 = 290

L = 290-144

L = 146 feet is the length

We can confirm this by saying

P = 2(L+W) = 2(146+144) = 2*290 = 580

Or we could say

P = 2L+2W = 2*146+2*144 = 292+288 = 580

or,

P = L+W+L+W = 146+144+146+144 = 580

y= -

just sum

10 + 10 = 20