SOLUTION: the length of a rectangle is three times its width, find the width if its perimeter is 100ft

Question 830863: the length of a rectangle is three times its width, find the width if its perimeter is 100ft
Found 2 solutions by JulietG, josmiceli:
Answer by JulietG(1812) (Show Source): You can put this solution on YOUR website!
We know that the perimeter (like a fence) is 2 pieces of the length and 2 pieces of the width. P = 2L + 2W
The problem tells us that L = 3W ("length is three times its width")
The perimeter is given as 100'.
.
Now we just have to plug in the values.
100 (P) = 2L + 2W
Substitute the value for L
100 = 2(3W) + 2W
Multiply
100 = 6W + 2W
Add
100 = 8W
Divide each side by 8
12.5 = W
.
Now that we know W, we can find L ("length is three times its width")
L = 3* W (12.5)
L = 37.5
.
Let's check to be certain.
P = 2(37.5) + 2(12.5)
P = 75 + 25
100 = 75 + 25
.
Success!
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Given:
Perimeter =
By substitution:
Perimeter =
Perimeter =

and

-------------
The width is 12.5 ft
check:

OK
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