Problem 3: A 50 per cent solution of solute B in solvent A is extracted with a second solvent Cin a countercurrent multiple contact extraction unit. The mass of C is 25 per cent that of the feed solution. Determine the number of ideal stages required, and the mass and concentration of the first extract if the final raffinate contains 15 per cent of solute. The liquid-liquid ternary diagram is given in figure 1 below. 00 B