## anonymous one year ago Algebra Question

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2. anonymous

If $\frac{ 3 }{ 4 } = \frac{ 6}{ x } = \frac{ 9 }{ y }$ , then x +y = ?

3. SolomonZelman

you can solve for x, and solve for y, by making the following conclusions out of your initial statement (what you wrote above). (Hope you know why they are valid) $$\large\color{black}{ \displaystyle \frac{3}{4}=\frac{6}{x} }$$ and $$\large\color{black}{ \displaystyle \frac{3}{4}=\frac{9}{y} }$$

4. anonymous

oh so this also follows the transitive property of equality

5. SolomonZelman

yes, if you have a=b=c then you can conclude that: a=b a=c or b=c

6. SolomonZelman

this way we can solve for x and solve for y. (Have you found any of the unknown variables) ?

7. anonymous

Yes I have :D After cross multiplying: 3x= 24 and 3y = 26 and then dividing both equations by 3 on both sides gave me x = 8 and y = 12 and therefore x + y = 12 + 8 = 20 Did I do this right or was there a mistake somewhere?

8. SolomonZelman

you mea 3y=27?

9. SolomonZelman

x=8 is correct, check your y.

10. SolomonZelman

yes

11. anonymous

hmm

12. SolomonZelman

3y=36 yu meant 36 not 26

13. SolomonZelman

so, y=12, x=8 x+y=8+12=20 RIGHT !!

14. anonymous

OH haha

15. anonymous

I was like hmm where did you get 27 from haha, thanks :)

16. SolomonZelman

Yes, I got confused by 26 there (I thought you meant 27, but the keyboard was off by the first digit.... In any case, you are always welcome:)