Question 179540: A concrete driveway has a perimeter of 280 feet. The length of the driveway is 20 feet more than 4 times its width. Find the length and width of the driveway by writing two equations with two variables, and solving the equations by either the addition method or the substitution method
Instructions
you must define the variables, create two equations, then solve those two equations using algebraic methods of addition or substitution.
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! Let x = width
and y = length
.
From:"A concrete driveway has a perimeter of 280 feet" we get:
2(x+y) = 280
2x+2y = 280
x + y = 140 (equation 1)
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From:"The length of the driveway is 20 feet more than 4 times its width."
y = 4x+20 (equation 2)
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Using the definition of y from equation 2 substitute it into equation 1 and solve for x:
x + y = 140
x + 4x+20 = 140
5x+20 = 140
5x = 120
x = 24 feet (width)
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Substitute the above into equation 2 and solve for y:
y = 4x+20
y = 4(24)+20
y = 96+20
y = 116 feet (length)
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