Taking a percentage off
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D
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Please follow the rules of posting in this forum, as enunciated at:
READ BEFORE POSTING
Please share your work/thoughts about this assignment.
Start with naming variables and writing equations \(\displaystyle \ \ \to \ \ \)
let the amount before tax = A
Total price = amount before tax + tax
continue.....
HallsofIvy
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"600(+20%= 720)" makes no sense! You have to have 20% of something! I suspect it is saying that the original amount was $600 and that 20% of 600 is 120 so that the total is 600+ 20$ of 600= 600+ 120= 720.
Let the original amount be "S". Then 20% of S is 0.20S. Adding that to S gives S+ 0.20S= 1.20S= 720. Divide both sides by 1.20.
Its from my course. The bill is for 720, part of that bill includes 20% sales tax. In order to accrue it, i need to remove the sales tax first. Its specifically that part which always confounds me, i know it can be worked out a couple of ways.
i know the answer is 600 as that is part of the answer that i have.
D
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So now you know how arrive at the desired number (600) from the given data (720 and 20%).
If you are still not clear - let us know exactly where you are stuck!
firemath
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Think about it. If there is 20% sales tax, then 720 is 120%.
this is one of the answers i was given, but its not clear to me.
Sorry if I have confused you. What you could also have done is taken 20% of the £600 to find the vat charge, which is £120, which again takes the net amount to £600, which might be an easier way for you to understand it?
The way I have done it is similar to the method we use in the markup and margin questions. Simply saying that the net amount would be 100%, so that makes the gross amount (ie net + VAT) 120% and to calculate the net you would multiply the gross amount by the 100/120%.
Well yes, but i cant just always sit and think, i need the correct calculation that i can memorise and use every time.
pka
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Let \(\displaystyle SP\) be the selling price of the item.
\(\displaystyle TX\) be the tax rate as a percent.
\(\displaystyle FP\) be the total final price.
Then \(\displaystyle FP=(1+TX)(SP)\)
We can see \(\displaystyle \dfrac{720}{1.2}=600\) SEE HERE
Steven G
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This is one of the most unclear threads I read in awhile.
You first ask how to get $600, then you say that you know how to get the $600. So what is confusing you? Did you read HallsofIvy's post. What did you not understand?
Let's work the other way first. Suppose something cost $400 and there is 15% sales tax. How do you compute the total cost?
Note that 3x+4x = (3+4)x = 5x and x+7x = 1x+7x= (1+7)x = 8x
What do you have to pay? Clearly you have to pay the $400 and you have to pay the sales tax which is .15*$400
So what do you end up paying? 400 + .15*400 = 1*400 + .15*400 = (1+.15)*400= 1.15(400) = $460
Most importantly, your final price is 1.15*400. How do go from 1.15*400 back to 400? You divide by 1.15.
That is \(\displaystyle \frac{1.15*400}{1.15}\) = 400, the price of the item before sales tax.
No thats not what a said. I read the instructions for the post, it says that if you know the answer to put it in. I needed to know how they got to the answer. I know there are a couple of ways to work it out. The way i was doing it was complicated. I need the most accurate, fast way of coming to the answer. I knew there was a simple calculation i was missing. The bill was for 720, sales tax was included at a rate of 20%. The answer in my book went on to discuss the rest of the question and skipped over how they calculated the pretax price of 600.
Whats not clear to me is that if i look up, on the internet how to subtract a percentage, the calculatIons as they have worked them out come to 576 if i apply it to this question. But i know that 576 is wrong.
lev888
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Yes, 576 is a correct answer, but to a different question: What do we get if we reduce 720 by 20%? Answer: 576. Initial amount is 720, that's what 20% is applied to.
The question you posted is very different: what was the initial amount to which we added 20% and got 720? 20% here is applied to that unknown amount, not 720.
Steven G
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What you discovered is that adding 20% to a price and then reducing the price by 20% does NOT bring you make to the original price.
Suppose an item costs $600. You raise the price by 20% (same as adding 20% for sales tax). That is you increase the price by 20% of $600 which is $120. Now the price is $720. Obviously if you now reduce the price by $120 you get back to $600. If you reduce the price by 20%, then you are reducing it by 20% of $720. Note that 20% of $720 is and should be greater than 20% of $600. 20% of $720 is $144. So the item now costs $720-$144 = $576.
Suppose an item costs $600. You raise the price by 20% (same as adding 20% for sales tax). That is you increase the price by 20% of $600 which is $120. Now the price is $720. Obviously if you now reduce the price by $120 you get back to $600. If you reduce the price by 20%, then you are reducing it by 20% of $720. Note that 20% of $720 is and should be greater than 20% of $600. 20% of $720 is $144. So the item now costs $720-$144 = $576.
Ok. That is very clear and makes sense. However to cement it in, im off to find some practice questions. Thank you
Steven G
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I am glad that what I wrote was very clear and even made sense! I'll show this post to my boss here on the forum and hopefully get a raise(?). A 10% increase would be nice. I just hope that after getting the 10% raise they do not decide to decrease my new salary by 10%.