Let quantities of two types of tea costing ₹ 18 per kg and ₹ 20 per kg be 5W kg and 3W kg. respectively.

Then, CP of tea = (18 x 5W) + (20 x 3W)
= 90W + 60W = 150W
SP of tea = 21 x 8W = 168W

Correct Option: D

Let quantities of two types of tea costing ₹ 18 per kg and ₹ 20 per kg be 5W kg and 3W kg. respectively.

Then, CP of tea = (18 x 5W) + (20 x 3W)
= 90W + 60W = 150W
SP of tea = 21 x 8W = 168W

Profit percent = [(168W - 150W) / 150W] x 100%
= (18/150) x 100% = 12%

Let the number of pens bought = 5 x 4 = 20
Then, CP = (4/5) x 20 = ₹ 16
and SP = (5/4) x 20 = ₹ 25

Correct Option: C

Let the number of pens bought = 5 x 4 = 20
Then, CP = (4/5) x 20 = ₹ 16
and SP = (5/4) x 20 = ₹ 25
∴ Gain = 25 - 16 = ₹ 9
Gain % = (9/16) x 100% = 56.25%

Cost price of 11 Articles = 10
Cost price of 1 Article = 10/11
and SP of 10 Articles = 11
∴ SP of 1 Article = 11/10
Now, gain = (11/10) - (10//11)
= (121 - 100)/110 = 21/110
And gain% = [(21/110) / (10/11)] x 100

Correct Option: D

Cost price of 11 Articles = 10
Cost price of 1 Article = 10/11
and SP of 10 Articles = 11
∴ SP of 1 Article = 11/10
Now, gain = (11/10) - (10//11)
= (121 - 100)/110 = 21/110
And gain% = [(21/110) / (10/11)] x 100
= (21 x 11)/11 = 21

(SP of 100 pens) - (CP of 100 pens) = SP of 40 pens
⇒ SP of 60 pens = CP of 100 pens.

Correct Option: E

(SP of 100 pens) - (CP of 100 pens) = SP of 40 pens
⇒ SP of 60 pens = CP of 100 pens.

Let CP of each pen = ₹ 1
Then, CP of 60 pens = ₹ 60
SP of 60 pens = ₹ 100

Gain = 100 - 60 = ₹ 40
∴ Gain % = (40/60) x 100 % = 66.67%

Here, a = 16, b = 12
According to the formula,
Required gain percent = [(a - b)/b] x 100

Correct Option: A

Here, a = 16, b = 12
According to the formula,
Required gain percent = [(a - b)/b] x 100
= [(16 - 12)/12] x 100
= (4/12) x 100
= 33¹/₃% (gain)