A man perchases certain number of toffees at 6 per rupee. and the same number of toffees at 7 per rupee. He mixed the toffs and sells them at 6 per rupee. What is his gain or loss percent?

CP₁ = ? 4000
SP₁ = 4000 x 135/100 = ? 5400 CP₂
SP₂ = 5400 x 80/100 = ? 4320
CP₁ < SP₂
Hence, profit earned here.
? Required gain = ( SP₂ - CP₁)
= 4320 - 4000 = ? 320

CP₁ =? 7500
? SP₁ = (7500 x 124)/100 = ? 9300 = CP₂
SP₂ = (9300 x 80)/100= ? 7440
? CP₁ > SP₁
Hence, loss is incurred in this transaction
? Require loss = (CP₁ - SP₂)
= 7500 - 7440
= ? 60

Given, gain% = 20
Different between SP and CP = 240
Now, gain% = [(SP - CP)/ CP] x 100
? 20 = [240/CP] x 100
? CP = 240 x 5
? CP = 1200
? SP = 1200 + 240 [? SP - CP = 240]
= 1440

let SP = N, then CP = 2N/3
Gain = (N - 2N/3) = N/3
&ther4; Gain % = [(N/3) / (2N/3)] x 100%
= (N/3) x (3/2N) x 100% = 50%

Let CP = N, then gain = N/6
According to the question,
N + N/6 = 322
? 7N/6 = 322
? N = 322 x 6/7 = ? 276

CP = 100/70 = x 6384 = ? 9120
To gain 30%, SP = 130% of 9120
SP = (130/100) x 9120 = ? 11856

Let cost price of article is CP.
According to the formula,
CP = [SP/(100 - Loss %)] x 100
CP = [(100 x 9549)/(100 - 55)]
= ? 21220

Let CP = 5N and SP = 3N
Loss = (CP- SP) = (5N - 3N) = 2N
Loss % = (2N / 5N) x 100 %
= 40%

SP of 20 eggs = ? 1 and gain = 30%
CP of 20 eggs = (1 x 100)/130 = ? 10/13
Now, ? 10/13 yields 20 eggs.
? ? 1 will yield (20 x 13)/10 = 26 eggs
Clearly, 26 eggs were bought for ? 1.

CP of 6 toffees = ? 1,
SP of 6 toffees = 150% of 1 = 150/100 = 3/2
? For ? 3/2, the number of toffees sold = 6
? For ? 1, the number of toffees sold = 6 x (2/3) = 4