Acd makes 581/2 revolutions in 2/4 min.
complete the unit rate.

In 2/4 minutes the number of revolutions a CD makes = 58 ½                                                                                        = 117/2
Then
In 1 minute the number of revolutions the CD will make = [(117/2)/(2/4) ] * 1                                                                                          = (117 * 4)/(2 * 2)                                                                                          = 117
So it can seen that the CD revolves at the rate of 117 revolutions per minute. I hope this is the answer you were looking for. The procedure for solving this problem is easy for you to understand i hope.

A CD makes 58 1/2 revolutions in 1/2 minutes.

A CD makes 58.5 revolutions in 0.5 minutes.

Multiply both numbers by 2.

A CD makes 117 revolution in 1 minute.