Working alone, machine X can manufacture 1,200 nails in 12 hours. Working together, machines X and Y can manufacture 1,200 nails in 6 hours. How many hours does it take machine Y to manufacture 1,200 nails working alone?
Choose the correct choice from the following
A) 3 9/17	B) 5 1/3	C) 7	D) 10 1/5	E) 12
rate of machine x = 1200/12   (1200/12 + y)6=1200   y=100   100 * t = 1200   t=12   12.
<result>E</result>
Working alone, machine X can manufacture 1,200 nails in 12 hours. Working together, machines X and Y can manufacture 1,200 nails in 6 hours. How many hours does it take machine Y to manufacture 1,200 nails working alone?