A Shopkeeper charges sales tax of x% upto Rs.2,000 and above it he charges y%. A customer pays total tax of Rs 320, when he purchases the goods worth Rs. 6,000 and he pay's the total tax of Rs. 680 for the goods worth Rs. 12,000. The value of (x-y) is:

Correct Answer: -2

          2000xX100 + 4000xY100 = 320

 

and     2000xX100 + 10000xY100 = 680

 

x = 4  and  y = 6

 

x-y = -2