So you want 0.1 mL to give you 200mcg of each, correct?
The vial contains 2mg of each, which is 2000mcg.
2000mcg / 200mcg = 10 doses in the vial.
10 doses * (0.1 mL / dose) = 1 mL of bac water.
Or, even easier than that, since the concentration of your previous vial was 2000 mcg/mL of each and your new vial has 2000mcg of each, then to achieve the same concentration, you obviously need 1 mL.
But you can use the method described above to determine the amount of bac water needed for any situation.