In a single stage extraction process, 10 kg of pure solvent (containing no solute A) is mixed with 30 kg of feed containing at a mass fraction x = 0.2. The mixture splits into an extract phase and a raf-finate phase containing at x = 0.5 and x = 0.05 respectively. The total mass of the extract phase is (in Kg)

• A. 6.89
• B. 8.89
• C. 10
• D. 8.25