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 Question from ata: My cost is 100 and I want to make 20% profit on my selling price (not 20% of the cost). So, what should be calculation formula? Let's say my cost is 493.71 and I want to make 53.28% profit on the selling price; so how to determine the selling price?

Hi Ata,

Some algebra helps solve this. Suppose your cost is $\$C$and the selling price is$\$S,$ your profit is then you want your $\$S - \$C.$ You want your profit to be 20% of your selling price so what you need is

$\S - \C = 0.20 \times \S.$

Add $C to each side to obtain $\S = 0.20 \times \S + \C$ and then subtract 0.20 ×$S from each side to get

$\S - 0.20 \times \S = \C.$

Thus

$0.80 \times \S = \C$

or, dividing both sides by 0.80

$\S = \frac{\C}{0.80}.$

Hence for the example you sent, if the cost is $\$C = \$100$ then

$\S = \frac{\100}{0.80} = \125.$

I hope this helps,
Penny

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