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## #1 2013-02-02 05:16:57

Al-Allo
Member
Registered: 2012-08-23
Posts: 324

### Proportion

I just have a little problem :

X   8
_= _
7   9

If I would want to solve for X, I would multiply by 7 for each side. Leaving x=56
___
9
But what I did is x=56
__
63
Could somebody explain me why it's wrong ?
Thanks

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## #2 2013-02-02 06:26:06

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,666

### Re: Proportion

When you multiply by 7 you cancel the 7 on the left but not the 9 on bottom right.

Correct thing to do is to cross multiply

9x = 56

x = 56 / 9

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2013-02-02 06:30:18

Al-Allo
Member
Registered: 2012-08-23
Posts: 324

### Re: Proportion

But I mean not canceling the 9 but multiplying it by 7, it's not a right thing to do ? Thanks

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## #4 2013-02-02 06:34:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,666

### Re: Proportion

If you multiply by 7 you are going to get:

x = 56 / 9 which is the same thing.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #5 2013-02-02 07:28:41

Al-Allo
Member
Registered: 2012-08-23
Posts: 324

### Re: Proportion

bobbym wrote:

If you multiply by 7 you are going to get:

x = 56 / 9 which is the same thing.

ok, I understood. Thanks

Last edited by Al-Allo (2013-02-02 07:30:14)

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## #6 2013-02-02 07:32:09

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,666

### Re: Proportion

Hi;

You are welcome.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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