Math for Meds problem! Help!

Hello!
I cannot solve this problem whatsoever.. so i'm asking for your help people. If anyone knows how to solve this would be greatly appreciated. Thanks!
Here's the problem:

"You have Lidocaine 2 grams in 500 cc IV fluid.

a. Calculate microdrip flow rate for a 2 mg/min drip. (drops/minute)

b. Calculate microdrip flow rate for 3 mg/min drip. (drops/minute)"

A microdrop set is always 60drops=1ml; 60drops/min=60ml/hr

a) drops/1min = 60drops/1ml * 500ml/2000mg * 2mg/1min = 30drops/1min
(multiply across the top. multiply across the bottom. divide the results)

b) drops/1min = 60drops/1ml * 500ml/2000mg * 3mg/1min = 45drops/1min
(multiply across the top. multiply across the bottom. divide the results)

***OR***

Put your problem "on the clock"

The clock method can be used on all mg/min meds (lidocaine and dopamine are 2 easy examples) flowing through micro tubing. Find the total concentration (exp. 2000mg/500ml = 4mg/ml). It will always be at the 60 position. 1/4 of the total solution will always be at the 15; 1/2 always at the 30; 3/4 always at the 45.

1mg/min @ 15
2mg/min @ 30
3mg/min @ 45
4mg/min @ 60

2000mg/500ml = 4mg/ml

a. 30drops/min (30ml/hr)
b. 45drops/min (45ml/hr)


I hope this makes sense. I can show it in person a whole lot better than I can write it out on an email

Great! Just what i thought. I've got those results after awhile but i wasn't sure if my technique was right. Thank you for clearing the things up.