It costs Rs. x each to make the first thousand copies of a compact disk and Rs. y to make each subsequent copy. If z is greater than 1,000, how many Rupees will it cost to make z copies of the compact disk?
Choose the correct answer.
A) 1000 x + yz	B) zx - zy	C) 1000 (z - x) + xy	D) 1000 (z - y) + xz	E) 1000 (x- y) + yz
Explanatory Answers   We need to find the total cost to make z copies, z &gt; 1000.   The first 1000 copies will cost Rs.x each. Or the total cost of first 1000 copies = Rs.1000x   The remaining z - 1000 copies will cost Rs.y each.   Or the cost of the z - 1000 = Rs.(z - 1000)y   Therefore, total cost = 1000x + zy - 1000y   = 1000(x - y) + yz   Answer 1000 (x- y) + yz
<result>E</result>
It costs Rs. x each to make the first thousand copies of a compact disk and Rs. y to make each subsequent copy. If z is greater than 1,000, how many Rupees will it cost to make z copies of the compact disk?