Two machines, Y and Z, work at constant rates producing identical items. Machine Y produces 23 items in the same time Machine Z produces 21 items. If machine Y takes 21 minutes to produce a batch of items, how many minutes does it take for machine Z to produce the same number of items? Choose the correct choice from the following choices
A) 6
B) 9
C) 9 1/2
D) 12
E) 23
rate z/rate y=21/23   time z/time y=23/21   (23/21)*21= 
<gadget id="calculator">(23/21)*21</gadget>
<output>23</output>
23 minutes   23
<result>E</result>
Two machines, Y and Z, work at constant rates producing identical items. Machine Y produces 23 items in the same time Machine Z produces 21 items. If machine Y takes 21 minutes to produce a batch of items, how many minutes does it take for machine Z to produce the same number of items?