A Tricky Percentage Math Problem

by Cathy
(Metamora, MI )


If someone wants to make $10.00 when selling an item and I get 40%. How much do I need to add to $10.00? It's not coming out when I add 40% to 10.00.

You cannot take 40% of 10 because that someone is not sharing 10.00 with you. He or she is willing to share a bigger amount. So you have to add something to 10 dollars. 40% of the new amount is your share

let x be what we add to 10 dollars and that is your share!

40% of (10 + x)= x

Notice that 40% of the new amount(10+x) has to equal to your share or x. Does that make sense?

0.40 (10+ x) = x
4 + 0.40x = x
4 = x - 0.40x
4 = 0.60x
x = 4/0.60 = 6.6666666
So you have to add 6.66666 to 10 to get 16.666666

Take 40% of 16.6666. Of course, it is equal to 6.66666 and 16.666666- 6.66666= 10
Not so easy problem. Good question Cathy!

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Apr 15, 2015
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SlimQuick
by: SlimQuick

Another great post, I appreciate all the work you put into this site, helping out others with your fun and creative works.

Dec 24, 2014
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Excellent!
by: Shaun Neruda

That was an interesting problem. I could not figure out the solution on my own. I always had trouble dealing with the calculations based on percentages. Anyway, you have given an interesting account. I’m quite impressed with the explanation.


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