How do I make 5 ml of a final concentration of 20 ug/ml of reagent A in 10% reagent B/ 1X reagent C?

Note: The stock of reagent A is at 1 mg/ml. Reagent C is purchased as 1X. Use the stock of undiluted Reagent B. How do I go about doing this and what will be my final answer/s? These are the only variables given and I haven't left anything out in the question. Thanks and I look forward to your replies.