Question

After selling 5 pens a shopkeeper purchases 2 pens with the profit obtained after selling 5 pens. If he earns 20
Rs. on selling a pen then find S.P. of a pen.​

Answer 1

Answer:

SP= Rs. 70

Step-by-step explanation:

let the buying price of each pen be denoted as $x$

and the selling price as $y$

Then, the profit made after selling one pen is $(y-x)$

If the profit earned after selling 5 pen is used to purchase 2 pens, then

$5(y-x)=2x\\5y-5x=2x\\5y-7x=0........................................ (1)$

If the profit of one pen is Rs 20, then

$y-x=20.....................................(2)$

solving for x and y in these equations;

y=x+20

subtituting this in eqn (1)

$5y-7x=0\\5(x+20)-7x=0\\5x+100-7x=0\\2x=100\\x=50$

then

$y=x+20\\y=50+20\\y=70$

Therefore SP= Rs. 70