As seen previously, with 200 mL of solvent₂ you extracted 240 particles of compound . One extraction with 200 mL gave a TOTAL of 240 particles.
(See figure on the right side).

If you extract twice with 100 mL of solvent₂,
you already know that with the first 100 mL of solvent₂, you extracted 200 particles of (see figure on the left side).

You still have 100 mL of solvent₁, containing 100 particles of . Now you add a second 100 mL volume of fresh solvent₂. According to the distribution coefficient K=2, you can extract 67 more particles from the remaining solution.

Organic Web Chem University of Alberta