Assume all CDs are equal in time.
If 21 CDs have X hours of music, how many minutes will Y CDs have?
Choose the correct choice from the following options
A) 21XY/60 B) 7/60XY C) 21/60XY D) 20XY/7 E) 7/20XY
21 C20XY/7s have X hours or 60*X minutes   1 C20XY/7 has time = 60*X/21 = 20X/7   Y C20XY/7 time in minutes = Y*20*X/7 = 20XY/7   Hence, the answer is 20XY/7.
<result>D</result>
Assume all CDs are equal in time.
If 21 CDs have X hours of music, how many minutes will Y CDs have?