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## Smokahontas 2 years ago Trapezoid problem? (Geometry)

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1. Smokahontas

I set up the equation as 3x+5=1/2[(7x+4)+4] but I got the wrong answer. I dont understand how to do it, please help?

2. sirm3d

what value of x did you get?

3. Smokahontas

I got 10, but the answer is 11. I dont know how to get 11 though..

4. sirm3d

ah, $$\overline{EF}$$ is asked. what did you get for x?

5. Smokahontas

I told you haha, I got 10...

6. sirm3d

something went wrong in your algebra. let's compare results. $3x+5=(1/2)[(7x+4)+4]\\2(3x+5)=(7x+4)+4\\6x+10=7x+8$

7. Smokahontas

Where did you get the 2 from? And where did the 1/2 go?

8. sirm3d

i multiplied the first equation by 2 to clear denominator

9. Smokahontas

That would've been better...but if you solve it like that wouldnt x=6?

10. sirm3d

6x+10-6x=7x+8-6x 10 = x + 8 10-8=x-8 2=x

11. sirm3d

$\overline{EF}=3x+5=3(2)+5=11$

12. sirm3d

uhm, the third line should read 10-8=x+8-8

13. Smokahontas

Oh I see...but I thought Line EF was half of line BC...?

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