Question

The cost price of 10pencil is the selling price of 8 pencils. what is profit percentage

Answer 1

CP of 10 pencils = x
CP of 1 pencil = x/10

SP of 8 pencils be x
Than 1 pencil = x/8 

Thus SP is greater than CP 
Gain = SP-CP
          = x/8 - x/10
            = 5x /40 - 4x /40
            = x/40

Gain % = Gain / CP *100
             = x/40 / x/10 *100
                = 25 %