While working alone at their respective constant rates, server B uploads 480 files in 4 hours and server Y uploads 480 files in 8 hours. If all files uploaded by these servers are the same size, how long would it take the two servers, working at the same time and at their respective constant rates, to process a total of 480 files?  Choose the correct choice from the following answers: A) 2 hr B) 2hr 20 min C) 2hr 40 min D) 5 hr 40 min E) 6hr
Server B processes 480/4= 
<gadget id="calculator">480/4</gadget>
<output>120</output>
120 per hour   Server Y processes 180/8 files per hour= 60 per hour   Total files processed per hour when B and Y work together = 120+60= 
<gadget id="calculator">120+60</gadget>
<output>180</output>
180 files per hour   480/180= 2 2/3 hours=2hr 40 min
<result>C</result>
While working alone at their respective constant rates, server B uploads 480 files in 4 hours and server Y uploads 480 files in 8 hours. If all files uploaded by these servers are the same size, how long would it take the two servers, working at the same time and at their respective constant rates, to process a total of 480 files?