Question

The cost price of 10 pens is equal to the selling price of of 9npens Find the profit or loss percentage

Answer 1

This can be simply done using an example.

Suppose we have 10 pens costing Rs.10 each
Cost of ten pens : 100
Selling price of 9 pens : 100

Selling price of 10 pens : 100/9 × 10 = 1000/9 = 111.11

Profit % = 111.11 - 100/100 × 100 = 11.11 %

Answer 2

Step-by-step explanation:

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The cost price of 10 pens is equal to the selling price of of 9pens Find the profit or loss percentage

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Let the C.P be 'x' & S.P be 'Y'

Then 10x=9y.........(1)

$\bold{ = > profit = \frac{y - x}{x} \times 100}$

$\bold{= > (\frac{y }{x} - 1) \times 100}$

From ..(1)

$Profit \:Percentage=( \frac{10}{9} - 1) \times 100 = \frac{100}{9} %$

$= > \frac{100}{9} = 11 \frac{1}{9}$%

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