Question

A dealer sells a toy for Rs 24 and gains as much percent as the cost price of the toy
find the cost price of toy
which mathematical concept is used in above problem. ​

Answer 1

sp=24

let cp be x

gain%=x%

gain%=sp-cp/100 * sp

=>x=24-x/x*100

=>

$x = \frac{24 - x}{x} \times 100 \\ x \times x = 2400 - 100x \\ x ^{2} = 2400 - 100x \\ {x}^{2} + 100x - 2400 = 0 \\ {x}^{2} + 120x - 20x - 2400 = 0 \\ (x + 120x)(x - 20) = 0 \\ x + 120 = 0 or \: x - 20 = 0 \\ x = - 120 \: or \: x = 20$

since cp cannot be negative

cp=20

Answer 2

Answer:

Your answer is 20

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