Markup calc

[Golfer]

Hi all, this has been buggin me all day and i still cannot solve it - Anyone up for a challeng?
Your challenge is this -
Calculate the Cost price of an item by entering the selling price and a markup percentage.
Seem simple? god i wish it was....
If you started with a COST price of 8.00 and add 25% markup you get 10.00
However - you can only use the selling price and the markup % in order to derive the cost price of 8.00
It also must work with any selling price and markup % you enter and still be mathamatically correct.

Been buggin the hell out of me!!!!

 

[plog]

So,

CostPrice + CostPrice*Markup = FinalPrice

Then by my magical and mystical powers of mathematics:

CostPrice*(1 + Markup) = FinalPrice

And finally:

CostPrice = FinalPrice/(1 + Markup)

Did I miss something?

 

[Golfer]

You appear to have used the cost price in the calc???
You cannot use the cost price in the calculation it HAS to be the product of the calculation.
You can only use the selling price of 10.00 and the markup price of 25% to derive the correct answer (8.00)
Believe me i've tried and always come up with 7.50 (which is wrong)

 

[plog]

I did not use the Cost Price in the calc, I used it in the equation. There's two sides to every equation, ergo, whatever you are solving for will always be in the equation.

Its actually pretty simple algebra: http://www.analyzemath.com/Algebra1/Tutorials.html

CostPrice = FinalPrice/(1 + Markup)

FinalPrice = 10, Markup=.25

CostPrice = 10/(1 + .25)
CostPrice = 10/1.25
CostPrice = 8

 

[Golfer]

Plog - Apologies you are correct, i was just being lazy. Had i actually plugged the equation i woudl have realised sooner.
I bow to the bigger brain - Thank you.

 

[Golfer]

Have attached the fruits of our labour in case anybody else finds useful.
The Margin calc was my own work but thanks should be made to Plog for the markup calc.
Plog - my margin calc is pretty ugly, maybe you can improve upon?

 

[Brianwarnock]

=((K7*M7)-K7)*-1

why not

=K7-(K7*M7)
or
=K7*(1-M7)


Brian

 

[Golfer]

You see, this is why i use this wonderful forum. So many brains so willing to help the mentally challenged.
Thank you Brian, your help as always is appreciated.