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I have the equation below which is correct:

$$\frac{(9650 - 9450)}{9650} \cdot 100 \cdot 5 = 10.36.$$

Supposed I want to solve for $9450$. So, substituting $x$ in:

$$\frac{(9650 - x)}{9650} \cdot 100 \cdot 5 = 10.36.$$

I tried solving the value of $x$ but I got $x = 9854.18$ which is wrong!

What will be the new formula to get the correct answer which should result in $x = 9450$?

Any help is greatly appreciated. Thanks in advance.

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    $\begingroup$ Just unpack it like in your previous question. This one is easier because it just has one X. We can't tell you what you have done wrong if you don't show your work. It clearly has to be less than $9650$ or the left side will be negative. $\endgroup$ – Ross Millikan Jul 31 '19 at 2:30
  • $\begingroup$ can you show the formula like you did in your last answer @RossMillikan $\endgroup$ – anagnam Jul 31 '19 at 3:12
  • $\begingroup$ I did unpack it and substitue it like your answer in my previous question @RossMillikan but I arrived at 9854.18 which is wrong. I followed your formula in your answer to my previous question. $\endgroup$ – anagnam Jul 31 '19 at 3:21
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The correct answer is 9450.052. Here's how to solve it:

First, divide both sides by 100 and 5. Second, multiply both sides by 9650, which is the denominator on the left side of the equation. This value (199.948) equals the difference between 9650 (in the numerator) and x. Symbolically, 9650-x=199.948. We add x to both sides to get 9650=199.948+x. Then, we subtract 199.948 from both sides to get x=9650-199.948. Putting this into the calculator, we have x=9450.052, which rounds to 9450.

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  • $\begingroup$ Don't forget you can use MathJax. $\endgroup$ – Toby Mak Jul 31 '19 at 2:58
  • $\begingroup$ where does 199.948 comes from @TobyMak $\endgroup$ – anagnam Jul 31 '19 at 3:14
  • $\begingroup$ How about you ask a separate question with full context, and explain exactly what you do not understand about the answers? $\endgroup$ – Toby Mak Jul 31 '19 at 3:39
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This is how I solve the value of X in:

$\frac{(9650-X)}{9650}$ * 100 * 5 = 10.36$

$Solving for X$. $$((9650 - X) / 9650) * 100 * 5 = 10.36\\ \frac{9650-X}{9650}=\frac {10.36}{500}\\ 500 \cdot 9650-500X=10.36X \cdot 9650\\ (500-10.36) \cdot 9650=500X\\ X=\frac{(500-10.36)\cdot 9650}{500}\\$$

and $X=9450$

And I cannot understand why people is making fun of downvoting questions instead of helping out newbies. such a shame!

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  • $\begingroup$ many thanks to @RossMillikan $\endgroup$ – anagnam Jul 31 '19 at 3:56
  • $\begingroup$ In your third line there is a mistake. It should be $10.36\cdot9650$ instead $10.36X\cdot9650$ that you wrote. $\endgroup$ – Michael Rozenberg Jul 31 '19 at 10:50
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I have the equation below which is correct:

Is it?

$\frac{(9650 - 9450)}{9650} \cdot 100 \cdot 5=$

$\frac {200}{9650}\cdot 500=$

$\frac {100,000}{9650} \approx 10.36$ but not exactly equal to $10.36$.

(It is exactly equal to $\frac {2,000}{193}=10\frac {70}{193}$.)

The solution to $\frac{(9650 - x)}{9650} \cdot 100 \cdot 5=10.36$ would be $x = 9450$ if your equation was correct but as you equation was close the solution will be close.

(The solution to $\frac{(9650 - x)}{9650} \cdot 100 \cdot 5=10\frac {70}{193}$ would be $x = 9450$.)

Let's unpack to and see what $x$ is:

$\frac{(9650 - x)}{9650} \cdot 100 \cdot 5=10.36$

$(9650-x) \cdot 100\cdot 5 = 10.36 \cdot 9650 = 99974=100,000-26\approx 100,000$

(you might not think $99974$ is that close to $100,000$ because it is off by $26$. But $26$ is a very small number compared to $100,000$. And $99974$ is exactly as close [proportionally] to $100,000$ as $10.36$ is to $10\frac {70}{193}$. $26$ is only $0.026\%$ of $100,000$ so it is actually very close.)

$9650 - x = \frac {99974}{500} = 199.948\approx 200$

$x - 9650 = -199.948\approx -200$

$x = 9650 - 199.948 = 9450.052 \approx 9450$.

So... I do not know where you made the mistake but I imagine it was simple arithmetic or punching numbers into a calculator error.

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It's $$\frac{9650-X}{19.3}=10.36$$ or $$9650-X=199.948$$ or $$X=9650-199.948$$ or $$X=9450.052.$$

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  • $\begingroup$ where does 19.3 comes from @Michael Rozenberg $\endgroup$ – anagnam Jul 31 '19 at 3:08
  • $\begingroup$ $\frac{1}{9650} \cdot 100 \cdot 5 = \frac{1}{19.3}$. $\endgroup$ – Toby Mak Jul 31 '19 at 3:09

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