Working alone, machine X can manufacture 1,000 nails in 12 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 800 nails working alone?
Choose the correct choice:	A) 6 6/7	B) 7 1/3	C) 7	D) 8 1/5	E) 9 4/7
rate of machine x = 1000/12   (1000/12 + y)5=1000   y=350/3   350/3 * t = 800   t=6 6/7   6 6/7.
<result>A</result>
Working alone, machine X can manufacture 1,000 nails in 12 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 800 nails working alone?