Computing Molarity without using M1V1=M2V2 equation?

A 0.09982M NaOH solution is used to titrate 100.0ml of a citric acid solution to a phenolpthalein endpoint. The titration requires 21.86ml of the NaOH solution. Compute the molarity of the citric acid solution. When 1 mole H3C6H5O7= 3 moles NaOH