Question

If selling price of 10 pens is equal to the cost price of 14 pens find gain per cent

Answer 1

$\mathfrak{Step-By-Step\:Explanation:}$

Let the selling price of 10 pens be Rs.x.

So the SP of 1 pen :

$\tt{=Rs.\dfrac{x}{10}}$

The Cost price of 14 pens = Sp of 10 pens = Rs. x.

So the CP of 1 pen :

$\tt{=Rs.\dfrac{x}{14}.}$

Selling price of 1 pen is greater than Cost price of 1 pen.

So

$\boxed{\bold{Gain=SP-CP}}\\\\\\\tt{Gain=\dfrac{x}{10}-\dfrac{x}{14}}\\\\\\\tt{=\dfrac{7x-5x}{70}}\\\\\\\tt{=\dfrac{2x}{70}=Rs.\dfrac{x}{35}.}\\\\\\\boxed{\bold{Gain\%=\dfrac{Gain\times 100}{CP}}}\\\\\\\tt{=\dfrac{\dfrac{x}{35}\times 100}{\dfrac{x}{14}}}\\\\\\\tt{=40\%.}\\\\\\\boxed{\boxed{\bold{Gain\%=40\%.}}}$