Question

pencils were bought 5 for Rs 4 and sold 4 for rupees 5 find the profit percent

Answer 1

We will be using simple unitary method to solve this question.

CP of 5 pencils = ₹ 4
CP of 1 pencil = ₹ 4 / 5 = ₹ 0.80

SP of 4 pencils = ₹ 5
SP of 1 pencil = ₹ 5 / 4
SP of 1 pencil = ₹ 1.25

Profit on 1 pencil = SP - CP
Profit on 1 pencil = ₹ 1.25 - ₹ 0.80
Profit on 1 pencil = ₹ 0.45

Hence,

Profit percentage = ( 0.45 / 0.80 ) * 100
Profit percentage = ( 45 / 80 ) * 100
Profit percentage = ( 45 / 8 ) * 10
Profit percentage = 450 / 8
Profit percentage = 56.25 %

Answer 2

Here is your solution

Given :-

➡pencils were bought 5 for Rs 4 .

➡sold 4 for rupees 5 .

Now using

unitary method to solve this question.

CP of 5 pencils = ₹ 4

CP of 1 pencil = ₹ 4 / 5 = ₹ 0.80

SP of 4 pencils = ₹ 5

SP of 1 pencil = ₹ 5 / 4

SP of 1 pencil = ₹ 1.25

Profit on 1 pencil = SP - CP

Profit on 1 pencil = ₹ 1.25 - ₹ 0.80

Profit on 1 pencil = ₹ 0.45

Now

Profit % = ( 0.45 / 0.80 ) × 100

Profit % = ( 45 / 80 ) × 100

Profit % = ( 45 / 8 ) × 10

Profit % = 450 / 8

Profit % = 56.25 %

Hence

Profit percentage  is 56.25 %

Hope it helps you