Question

A shopkeeper earns a profit of $Rs2$ by selling a pen and incurs a loss of $50paise$ per pencil and loss of $15paise$ per eraser while selling old stock. On a particular day, he earns a profit of $Rs10$. If he sold $10$ pens and number of pencils and erasers he sold are in the ratio $7:10$, then find the number of pencils and eraser he sold that day.

Answer 1

By selling a pen gain is $Rs.2$
and by selling a pencils, he loses $50$ paise
and an eraser, he loses $15$ paise
On one day, he gain $=Rs.10$
On that day he sold $10$ pens and pencils and erasers in the ratio of $7:10$
On ten pens, his gain $=10\times 2=Rs.20$
loss on pencils and erasers $=Rs.20-Rs.10=Rs.10=1000$ paise
Ratio in pencil and eraser $=7:10$
Let number of pencils $=7x$, then eraser $=10x$
$7x\times 50+10x\times 15=1000$
$\Rightarrow 350x+150x=1000$
$\Rightarrow 500x=1000$
$\Rightarrow x=2$
Numbe rof penciles $=7\times 2=14$
and number of erasers $=10\times 2=20$