CaCO₃ precipitate can be produced by reaction of an aqueous solution of Na₂CO₃ and CaO, the byproduct being NaOH. Following decantation, slurry leaving the precipitation tank is 5 wt% CaCO₃, 0.1 wt% NaOH, and the balance water. One hundred thousand lb/h of slurry is fed to a two-stage, continuous, countercurrent washing system to be washed with 20,000 lb/h of fresh water. Underflow from each thickener will contain 20 wt% solids. Determine % recovery of NaOH in the extract and wt% NaOH in the dried CaCO₃ product. Is it worthwhile to add a third stage?