rahul earns a profit of Rs.1 by selling one pen and suffers a loss of 50 paise by selling one pencil.

(a) one day he earns Rs.5,if he sold 25 pens,how many pencil did he sell?(

b) the next day he earns neither profit nor loss. of he sold 30 pencils, how many pens did he sell?

given: rahul earns a profit of Rs. 1 by selling one pen and suffers a loss of 50 paise by selling one pencil.

(a)

he sold 25 pens, therefore profit earned by selling pens = 25*1= 25 Rs.

he earns Rs. 5.

therefore  loss on that day by selling pencil = Rs. 25 - Rs. 5 = Rs. 20 

loss by selling one pencil = 50 paise = Rs. 0.50 

therefore the number of pencils sold by him =

thus he sold 40 pencils .

(b)

if he sold 30 pencils .

loss by selling 30 pencils = Rs. 30*0.50 = Rs. 15

since he made no profit no loss, therefore profit by selling pens = Rs. 15

thus the number of pens sold by him = 15

hope this helps you.

cheers!!