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We know that,
If a product is sold at a higher price than the price it was bought, then that is called gain or profit.
Selling price : The price at which the product is sold.
Cost Price : The price at which the product is bought.
We say the profit is occurred when selling price is more than the cost price .
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Rewrite as,
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on transposing to RHS , we get
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Hence, the answer for given blank is .