Question

if cost of 21 pencil =selling price of 25 pencils
what is the loss percent
 

Answer 1

21 cp= 25sp
cp=25/21sp
loss=cp-sp 
      =25/21sp-sp
      =4/21sp
loss %= (4/21sp)*(21/25sp)*100
           =8% 

Answer 2

CP=21 SP=25 SO LOSS=21-25/25*100=-16