Maha Bazaar offers 20% discount on bags which have been

Maha Bazaar offers 20% discount on bags which have been marked 50% above the cost price. Amarnath pays ₹ 840 for a bag. Then the cost price of the bag is

Let the cost price be ₹ 100.
∴ Marked price = ₹ 150

S.P. =	150 × 80	= ₹ 120
	100

when S.P. = 120, C.P. = 100
when S.P. = 840

C.P. =	100	× 840 = ₹ 700
	120

2nd method to solve this question.
Here, r = 50%, r₁ = 20%,
S.P. = ₹ 840

Gain % =	r ×(100 − r₁)	− r₁
	100

Gain % =	50 × (100 − 20)	− 20
	100

Gain % =	50 × 80	− 20
	100

Gain % = 20%
We know that ,

Gain % =	S.P. − C.P.	× 100
	C.P.

20 =		840 − p		× 100
		p

20p= 84000 – 100p
120p = 84000
p = 700
∴ C.P. = ₹ 700