The simplest way to do this math is using the formula: C1V1 = C2V2

For your target solution: 190 µg in 200 µl = (950 ng/µl)(200 µl)

• Protein1: (952.62 ng/µl)(X µl) = (950 ng/µl)(200 µl) ... X = 199.44 µl stock + 0.56 µl H2O
• Protein2: (1015.09 ng/µl)(X µl) = (950 ng/µl)(200 µl) ... X = 187.18 µl stock + 12.82 µl H2O

This website has a nice calculator that you can use in the future:

https://www.physiologyweb.com/calculators/dilution_calculator_mass_per_volume.html

You probably ought to convert the concentrations into molarity first. This way it will be true 1:1 ratio.

Use this formula: Mass (g) = Concentration (mol/L) x Volume (L) x Molecular Weight (g/mol)

Then do the C1V1 = C2V2 calculation that John Hardy Lockhart mentioned.

thanks for good suggestions