Question

If cost price of 25 books is equal to selling price of 20 books, calculate the gain or loss per cent

Answer 1

let
c.p. of 25books be 100
therefore cp of 1 book is 100/25=4
so sp of 20 book is 100
therefore sp of 1 book is 100/20=5
gain =sp -cp =5-4=1
gain%=1/4*100%=25%
ans 25%

Answer 2

let's assume
c.p. of 25books =100

therefore cp of 1 book is 100/25=4

so, sp of 20 book =100

therefore sp of 1 book is 100/20=5

gain =sp -cp =5-4=1

gain%=1/4*100%=25%

=25%
Hopes it help