Question

You are going to make three shelves for your father and have one piece of lumber 20 feet long. Your plan is to make the top shelf half a foot shorter than the middle shelf and to have the bottom shelf half a foot shorter than twice the length of the top shelf. How long is each shelf? t= length of the top shelf t=m-1/2 m = length of middle shelf b = length of bottom shelf. B=2t-1/2 t+m+b=20

Answer 1

The top shelf is 5 feet, the middle shelf is 5.5 feet and the bottom shelf is 9.5 feet

Explanation:

Let t= length of the top shelf, m = length of middle shelf and b = length of bottom shelf.

Therefore:

t = m - 1/2; m = t + 1/2

Also, b = 2t - 1/2

The total of the three shelves is 20 feet, therefore:

t + m + b = 20

Substituting:

t + t + 1/2 + 2t - 1/2 = 20

4t = 20

t = 20/4

t = 5 feet

m = t + 1/2 = 5 + 1/2 = 5.5 feet

b = 2t - 1/2 = 2(5) - 1/2 = 9.5 feet

The top shelf is 5 feet, the middle shelf is 5.5 feet and the bottom shelf is 9.5 feet