SP of 20 eggs = ₹ 1 and gain = 30%
CP of 20 eggs = (1 x 100)/130 = ₹ 10/13
Now, ₹ 10/13 yields 20 eggs.

Correct Option: D

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

Correct Option: C

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

Let cost price = ₹ N
According to the question,
N x [(100 + 40)/100] = 700,

Correct Option: D

Let cost price = ₹ N
According to the question,
N x [(100 + 40)/100] = 700,
⇒ N = (700 x 100)/140 = 500
∴ New selling price = 500 x (100 + 10)/100
= 5 x 110 = 550
= ₹ 550

SP of cellphone = ₹ 2400
∴ CP of cellphone = 2400 x [100/(100 + 25)] = ₹ 1920
∴ Required percentage profit = [(2040 - 1920)/1920] x 100

Correct Option: B

SP of cellphone = ₹ 2400
∴ CP of cellphone = 2400 x [100/(100 + 25)] = ₹ 1920
∴ Required percentage profit = [(2040 - 1920)/1920] x 100
= 6.25%

Let the CP = N
According to the question, (110N/100) - (80N/100) = 12

Correct Option: B

Let the CP = N
According to the question, (110N/100) - (80N/100) = 12
⇒ (11N/10) - (4N/5) = 12
⇒ 11N - 8N = 120
∴ N = 120/3 = 40
∴ CP = ₹ 40