A shopkeeper increases the price of an object by 40% and

A shopkeeper increases the price of an object by 40% and then sells it at 25% discount on the marked price. If the selling price of such an object be Rs. 2100, its cost price for the shopkeeper was

Here , Selling price of an object = Rs. 2100
a = 40% , b = -25%
Using the given formula,

Effective percentage =		a + b +	a × b		%
			100

Percentage effect =		40 − 25 −	40 × 25		%
			100

Percentage effect = (15 – 10)% = 5%
If the C.P. of article be Rs. y,

then, y ×	105	= 2100
	100

⇒ y =	2100 × 100	= Rs. 2000
	105