Working alone, machine X can manufacture 1,000 nails in 20 hours. Working together, machines X and Y can manufacture 1,000 nails in 5 hours. How many hours does it take machine Y to manufacture 1,000 nails working alone?	Choose the most appropriate option: A) 3 9/17 B) 5 1/3 C) 7 D) 7 1/5 E) 6 2/3
rate of machine x = 1000/20   (1000/20 + y)5=1000   y=150   150 * t = 1000   t=6 2/3   E. 6 2/3
<result>E</result>
Working alone, machine X can manufacture 1,000 nails in 20 hours. Working together, machines X and Y can manufacture 1,000 nails in 5 hours. How many hours does it take machine Y to manufacture 1,000 nails working alone?