Question

If cost price of 25 books is equal to the selling price of 20 books , calculate the gain or loss percent.(please solve it quickly .)

Answer 1

cost price=c.p
selling price=s.p

c.p×25=s.p×20
c.p/s.p=4/5

profit Percentage=(s.p-c.p)/c.p*100

profit=(5-4)/4*100=25%

Answer 2

The gain percent is 25%.

Solution:

Let C.P. of a book = Rs. X

So, C.P. of 25 books = Rs. 25 X

And,

S.P. of a book = Rs. Y

So, S.P. of 20 books = Rs. 20 Y

Given that

25X = 20Y

$\frac{X}{Y}=\frac{25}{20}=\frac{4}{5} \ldots \ldots \ldots \ldots(1)$

We know that,

$\ Profit \%=\left(\frac{profit}{c.P}\right) \times 100$

$=\left\{\frac{S . P-C . P}{C . P}\right\} \times 100$

$\ Profit \%=\left\{\frac{S . P-C . P}{C . P}\right\} \times 100$

$\ Profit \%=\left\{\frac{Y-X}{X}\right\} \times 100$

$\ Profit \%=\left(\frac{Y}{x}-1\right) \times 100$

[Since$\frac{x}{Y}=\frac{4}{5}$]

$\ Profit \%=\left(\frac{5}{4}-1\right) \times 100$

$\ Profit \%=\left(\frac{5-4}{4}\right) \times 100$

$\ Profit \%=\frac{1}{4} \times 100$

$\ Profit \%=25 \%$

By selling the books as per the cost price and selling price given in the question, the gain is 25 percentage.