CHEMISTRY QUESTION about titration and concentration?

The formula to be used is N1V1=N2V2 which reduces to ------ M1aV1=M2bV2 , where M1 ,V1 are molarity & volume of base & a is acidity of base which is 2 ; and M2 ,V2 are molarity & volume of acid & b is basicity of acid which is 1. On substitution we get o.16*2*25=32*M*1 , Which gives conc of acid to be 0.25 mol/L .