A shopkeeper gives 2 kite free to a customer on purchase of 30 kites. If he doubles the discount, how many kites should he give free on purchase of 7 kites?

1

No. of kites free = 2

No. of kites sold = 30 + 2 = 32

Sale = 32 kites (constant)

ATQ, shopkeeper did not increase sale but double the discount only.

It means no. of articles sale will be 32 kites but he gives 4 kites free instead of 2.

Therefore, 

on selling 32 kites, free kites = 4

on selling 8 kites, free kites = 1

Hence, on purchase of 7 kites, 1 kite will be free.