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Question

Answers

A) Rs.$18$

B) Rs.$20$

C) Rs.$21$

D) Rs.$27$

Answer

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Given, there is $20% $ discount on list price.

So let us assume the list price is Rs.$100$ then using the formula - S.P. =${\text{List price - discount}}$, we can find the S.P.

On putting the given values, we get

$ \Rightarrow $ S.P. =$100 - 20$

On subtraction, we get

$ \Rightarrow $ S.P.$ = 80Rs.$

This means for S.P. of Rs.$80$, the list price is Rs.$100$

Then for S.P. Rs.$1$, list price is $ = \dfrac{{100}}{{80}}$

So I f S.P. is Rs. $24$then the list price will be $ = \dfrac{{100}}{{80}} \times 24$

On solving, we get

List price=$ = \dfrac{{100}}{{80}} \times 24 = 10 \times 3$

List price $ = {\text{Rs}}.30$

Now we have to find $30\% $ discount on list price,

We already know that list price so,

$30\% $ of $30 = \dfrac{{30}}{{100}} \times 30$

On solving the equation, we get

$30\% $ of $30 = 3 \times 3 = 9$

So discount=$9$ Rs.

We have to find the S.P. which results in $30\% $ discount on list price. We know the formula,

S.P. =${\text{List price - discount}}$

On substituting the given values we get-

S.P. =$30 - 9 = 21$ Rs.

Hence, for S.P. of Rs.$21$ there is $30\% $ discount on list price.

$ \Rightarrow {\text{SP = M}}{\text{.P}}{\text{. - }}\dfrac{{{\text{M}}{\text{.P}}{{. \times Discount\% }}}}{{100}}$ to find S.P.

On putting the given values in the formula we get,

$\

\Rightarrow {\text{S}}{\text{.P}}{\text{.}} = 30 - \dfrac{{30 \times 30}}{{100}} = 30 - \left( {3 \times 3} \right) \\

\Rightarrow {\text{S}}{\text{.P}}{\text{.}} = 30 - 9 = 21 \\

$

So using this formula we can find the value of S.P.=$21$ Rs.