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January 30, 2015

January 30, 2015

Posted by **G** on Friday, February 15, 2008 at 10:59am.

A=area of a trapezoid

b1=width at the top

b2-width at the bottom

h=height

A 7-foor tall trapezoid has 42 square feet of area. If is is 9 feet wide at the bottom, how far across is it at the top?

- Algebra -
**Guido**, Friday, February 15, 2008 at 11:05amI will set it up for you and you can simplify.

A = 42

h = 7

b2 = 9

I will plug and you can chug.

42 = 1/2(b1 + 9)(7)

Solve for b1, which is read "b sub one."

Can you take it from here?

- Algebra -
**G**, Friday, February 15, 2008 at 11:09amThank you for your response. I can set up and calculate. The book says I should be getting 3 feet as my answer. That is not what I am getting.

- Algebra -
**Guido**, Friday, February 15, 2008 at 11:13amHere it is:

First multiply 7 x 1/2 = 7/2.

We now have this equation:

42 = 7/2(b1) + 9)

Simplify the right side of the equation and the whole thing becomes

42 = 7/2(b1) + 63/2

Subtract 63/2 from 42.

42 - 63/2 = 10_1/2

We now have:

10_1/2 = 7/2(b1)

10_1/2 divided by 7/2 = b1

3 feet = b1

Done!

- Algebra -

- Algebra -

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