How Much Substance in One Drop of Solution?

[coolname]

I'm looking for a set of equation(s) to solve the following problem:

Given 5 mg of a substance dissolved in 30 ml of liquid, how much of the substance will be present in 1 drop of water of the solution? Given one drop of water is equal to 0.050 ml.

Thank you. This is not homework, just a request to know the appropriate equation to solve the above question.

 

[adjacent]

If 5mg get's dissolved in 30ml of water,what is the mass of water in 0.05ml of water?
Hint: 30ml is 5,what is 0.05ml?