# Solving a formula to help with my sister's work

Discussion in 'Algebra' started by Steve Downing, Feb 24, 2023.

1. ### Steve Downing

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Hi there, first time poster here. If I can solve this problem, I can save my sister countless hours in her job, which is great because she's raising two kids and keeping house and so on. At least, that's the plan. I'm working on a function for a spreadsheet she has. Before I do that, I need to crack a formula, from which I will derive said function.

Here's my working so far. As far as I can tell (I'm a gardener by trade and certainly no mathematician) If I can isolate PT, everything else should domino from there and I can automate a huge chunk of the spreadsheet work.

Steve

Steve Downing, Feb 24, 2023
2. ### phillip1882

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Feb 26, 2023
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Pt = Pw +C +1.05*Pt -(Pw+C+A)
-0.05 Pt = Pw +C -(Pw+C+A)

phillip1882, Feb 26, 2023
3. ### Steve Downing

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Feb 24, 2023
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Thanks, phillip. I'll plug that in and see what comes of it.

Steve Downing, Feb 28, 2023
4. ### Steve Downing

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Feb 24, 2023
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Having worked with this a bit more, this is where I am now. I hope my algebra work is more or less okay. The problem is that all the key variables, as far as I can tell, cancel out. It stands to reason that the total price (Pt) of the item should at least in part be based on the wholesale price (Pw), but that's not reflected in the final equation.

I'm really stumped. I suspect the problem is how the profit margin (M) is included in the equation, or at least how I've substituted the other variables into it in an attempt to make isolating Pt easier.

The reason I've had to farm this out at all is because the company wants the profit margin to be 10% of the final sale price, after the third-party firm has taken their cut (A) and the costs (C) have been deducted. However, in order to determine the final sale price (Pt), one needs to know the profit margin. This leads to a circular dependency problem where the question is conditional on the answer and vice versa. So far, my sister has been getting round this by using brute guess work to enter Pt figures until the profit comes back at =>10%. However, this is very cumbersome and if there's a way to automate the process, it would make her job so much easier.

Thanks so much for your time,

Steve

Steve Downing, Mar 5, 2023