Question

if selling price of 5 pens is equal to cost price of 4 pen then the gain or loss percentage is

Answer 1

cp of 4 pens = sp of 5 pens
let cp of 4 pens = x
then cp of 1 pen = x/4
cp of 5 pens =x/4×5=5x /4

sp of 5 pens =x
ATQ
sp<cp
so loss =5x/4-x=x/4
loss% =(x/4)÷5x/4 ×100 =20 %