hello "i need some help"

Im taking Pharmacology and we are in some converstions and im a little lost i was wondering if some one could help the problem reads
Order: Phenobarbital gr 1/6 p.o t.i.d
Supply: phenobarbital elixir 20mg per 5 ml
Give: _____________ ml
im not sure how to put it in the converstion
i know that gr1/6 is 10mg
but a little lost from there (i think im just over thinking it) but if you could help i would be so greatful !:uhoh21: 
About redaries
Joined: Oct '05; Posts: 15
right now i dont have one but im hoping to get one soon in a doctors office. 
Oct 7, '05Dang, girl!! You did the hard part
Okay, if there are 20 mg in 5 mL, and you want to give 10 mg, set it up:
20 mg/5 mL = 10 mg/X mL (I hope you know these are over each other..I can't get it to print right)
Cross multiply to get 20X=50...Divide 20X by 20 to get the X by itself. Whatever you do to one side of the equation, you have to do to the other, so divide 50 by 20, too. X=50/20 or 2.5 mL
Was that clear as mud?? 
Oct 7, '05i guess i dont understand how to get the 20x=50 that is where im confused i guess
Quote from truesnDang, girl!! You did the hard part
Okay, if there are 20 mg in 5 mL, and you want to give 10 mg, set it up:
20 mg/5 mL = 10 mg/X mL (I hope you know these are over each other..I can't get it to print right)
Cross multiply to get 20X=50...Divide 20X by 20 to get the X by itself. Whatever you do to one side of the equation, you have to do to the other, so divide 50 by 20, too. X=50/20 or 2.5 mL
Was that clear as mud?? 
Oct 7, '05Lets see if my brain is working right 10mg/20mg X 5ml= 2.5 ml
Quote from redariesi guess i dont understand how to get the 20x=50 that is where im confused i guess