SOLUTION: im having a hard time with this problem,please help! if the length of a rectangular parking lot is 20 meters less than twice its width,and the perimeter is 800 meters,find the leng

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Question 262852: im having a hard time with this problem,please help! if the length of a rectangular parking lot is 20 meters less than twice its width,and the perimeter is 800 meters,find the length of the parking lot.
Found 2 solutions by josmiceli, dabanfield:
Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
Let = the length in meters
Let = the width in meters
Let = perimeter in meters
given:
m
m
-------------------
The problem is to find
The formula for the perimeter of a rectangle is:

Substitute the given value for in this equation

m
Now substitute this value in given equation

The length of the parking lot is 260 m
check answer:

OK

Answer by dabanfield(803) (Show Source):
You can put this solution on YOUR website!
im having a hard time with this problem,please help! if the length of a rectangular parking lot is 20 meters less than twice its width,and the perimeter is 800 meters,find the length of the parking lot.
Let w be the width and l the length of the parking lot. Then we have:
1.) Perimeter = 2*w + 2*l = 800
2.) l = 2w - 20
Let's rewrite these two equations:
1.) 2w + 2l = 800
2.) 2w - l = 20
Subtracting equation 2.) from equation 1.) we have:
3*l = 780
l = 780/3 = 260
Calculate w from 2.:
2*w - 260 = 20
2w = 280
w = 140