Take a basis one liter solution

LP moles = 0.1mole

LP molar mass = 106.39 gm/mole

Mass of LP = 106.39*0.1= 10.639 gm

SI moles = 0.05 mole

SI molar mass = 149.89 gm/mole

Mass of SI = 149.89*0.05 = 7.494 gm

Now assume the mass of 20% PVP = x gm

20%= x / (x +10.639 gm + 7.494 gm)

x = 4.533 gm

Best regards

You can find the solution by visiting the following web sites:

https://worldwidescience.org/topicpages/s/sodium+borohydride+solution.html

https://www.science.gov/topicpages/a/ae2+anion+exchanger.html

https://www.science.gov/topicpages/a/anion-exchange+chromatography+hpaec.html