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A container is $\frac45$ full. After $3$ liters of its contents are poured out, the container is $\frac34$ full. How many liters would need to be poured back in to refill the container?

I have tried to solve it this way: $$\frac45x = 3-\frac34x$$

But it seems to give a wrong answer.

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Replace the minus sign with a plus sign. –  naslundx Mar 29 at 19:29

2 Answers 2

up vote 4 down vote accepted

$\frac{4}{5}x-3=\frac{3}{4}x$

Hence $\frac{1}{20}x=3$, then $x=60$. So you have to refill with $\frac{60}{4}=15$.

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Why you didvided by 4 to 60 –  SSK Mar 29 at 19:34
1  
Because the container can contain $60$ liters, then we know it is $\frac{3}{4}$ full, hence to make it full we have to add $\frac{1}{4}$ of its capacity –  Stefano Mar 29 at 19:35

Should be $\frac45x-3=\frac34x$ instead of what you put :)

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Thanks for the edit, some times can't be bothered to typeset properly if it's simple (I'm on my phone) –  ellya Mar 29 at 19:37

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