Compute the cec if soil is titrated with naoh

Question

100 g soil was completely saturated with Al⁺³ (100% of the CEC is occupied with Al⁺³).  Any excess Al⁺³was leached from the soil sample.  The exchangeable Al⁺³ was then exchanged with K⁺ by adding 1N KCl.  The Al⁺³ in the extract was determined by titration with 150 ml of 0.15 N base.  Calculate the CEC.

A soil is 75% saturated with Ca⁺² + Mg⁺² + K⁺.  50 g of this soil is titrated with 20 ml of 0.1 N NaOH.  Calculate the CEC.