Question

A shopkeeper earns a profit of ₹2 by selling new register and incurs a loss of ₹1.20 per register of old stock. in a particular day incurs loss of ₹4, he sold 10 new registers. how many old registers did he sell on that particular day.

Answer 1

Given that when one pencil is sold, the shopkeeper gets a loss of 40 paise and on selling 1 pen the shop keeper get a profit of Re 1
(1)
If she sold 45 pens then the profit made by her = 45 x 1 = Rs 45 rupees.
Given that she got a loss of Rs 5.
This implies that means she sold some pencils. Hence she got loss on selling those pencils.
On selling those pencils She got a loss of Rs 50 (Since already she got profit Rs 45)
Let the number of pencils sold be x.
On selling 1 pencil, loss incurred = 40 paise
On selling x pencils, loss incurred = Rs 50
= Rs 5000
Hence (1x 5000) = 40x
⇒ x = 5000/40 = 125
Thus number of pencils sold in the month is 125.

(2)
Given that she makes neither profit nor loss.
Hence profit made by selling pens = Loss got on selling the pencils à (1)
Given 70 pens are sold.
Profit made by selling these pens = 70 × Re 1
= 70 ×100 paise= 7000 paise.
Loss by selling x pencils = x × 40 paise
Equation (1) becomes,
7000 paise = 40x paise
⇒ x = 7000/40 = 175
Thus number of pencils sold in the month is 175