another word problem

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tRNA

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might seem easy for u, not for me

an eight lane highway costs $7500,000 per mile (5280ft). If each lane measures 11ft across, how much would it cost to pave a square mile of highway? answer: 450,000,000
plz explain how you get the length of that highway, thanks

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Well, im not sure all the minor steps a real math teacher would do, but heres how I solve it.

8 lane highway, 11 feet per lane, thats 88 feet wide. Divide 7,500,000 per mile by 88 and you now have how much it costs to make a mile long highway 1 foot wide. You dont need this information however, you need a highway 5280 feet wide to make a total of 5280 by 5280. So you take 7,500,000 divide it by 88 and multiply by 5280 for your answer.
 
You have 88ft across and it wants to know how much it costs for a square mile. You know how much it costs per mile in length. So you need the length.

Area = 1 square mile = 5280ft * 5280ft.
Area = length * width
5280^2 ft^2 = length * 88ft
5280^2 / 88 ft = length

Convert to miles by dividing this by 5280 ft:

5280/88 = length (in miles) = 60 miles.

Now 60 miles * $7,500,000/mile = your answer.
 
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