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Question
QUESTION: A bookshelf is to be constructed with 4 shelves.  The height is 3 feet more than the width.  

Amount of wood available- 30 feet.

Calculate dimensions of the bookcase.

Thanks for your assistance.

ANSWER: How do you count the shelves? Do the top and bottom count?  Only the bottom?
Or are there 4 *movable* shelves between the top and bottom ones that comprise
the frame?

It is important to know in order to answer the question.

Abe

---------- FOLLOW-UP ----------

QUESTION: The top and bottom count- none are movable.

Thanks again.

Answer
In that case...

Let x=the width of the bookshelf (in ft), so that x+3 = the height (in ft)

4 shelves requires 4x ft of wood, and 2 sides (for the height) require 2(x+3) ft.

Adding these we get: 4x + 2(x+3)= 30, neglecting the thickness of the wood.
==> 4x+2x+6=30 ==> 6x=24 ==> x=24/6 = 4 ft

Width = 4 ft, Height = 7 ft

Abe

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Abe Mantell

Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

Experience

Over 15 years teaching at the college level.

Organizations
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook

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