Question

A shopkeeper earns a profit of Rs.1 by selling a pencil and loss of 20 paisa by selling an eraser. (i) In a given day he had a loss of Rs.10. On this day, he sold 35 pencils. How many erasers were sold on this day. (ii) Next day, he earn a profit of Rs.25. On this day he sold 100 erasers. How many pencils did he sell.​

Answer 1

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(i) let no. of eraser sold be x

total loss = rs 10

10= loss by eraser - profit by pencil

10= (0.10x) - (35×1)

10= 0.10x -35

45=0.10x

x=450

so 450 erasers were sold that day

(ii) let no. of pencil be y

total profit = rs 25

25= profit by pencil - loss by eraser

25=( 1× y) - (100× 0.10)

25=y-10

35=y

so 35 pencils were sold that day

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Answer 2

Answer:

i) 225 Erasers

ii) 45 Pencils

Step-by-step explanation:

i) For 1 pencil the profit is = 1 rupee = 100 paise

∴  for 35 pencils the profit is = 35 x 1

                                               = 35 rupees

                                               = 35 x 100 = 3500 paise

Now,

Loss in one Eraser = -20 paise

∴ Loss in x number of Erasers = -20x

Total loss on that day is = -10 rupees

                                        = -10x 100

                                        = -1000 paise

According to the question:

Total Loss= (Loss on Eraser) + (Profit on Pencils)

-1000 = (-20x) + (3500)

-20x = -1000 - 3500

-20x = -4500

20x = 4500

x= 4500/20

x= 225

Hence, He sold 225 Erasers on that day.

ii) Erasers sold on that day = 100

Loss by 1 Eraser = -20 Paisa

 ∴ Loss by 100 Erasers = -20 x 100

                                       = -2000 Paisa

Now,

Total profit on that day = 25 rupees

                                      = 25 x 100

                                      = 2500 paisa

Now,

Profit by one Pencil = 1 rupee = 100 Paisa

∴ Profit by x Pencils = 100 x

According to the question:

Total Profit = (Profit by Pencils) + (Loss by erasers)

2500 = (100x) + (-2000)

100 x = 2500 + 2000

100 x = 4500

x = 4500/100

x = 45

Hence, he sold 45 Pencils.