NH2CH2COOH --(HCl)-->x1--(NaOH)-->x2--(HCl)-->x3

1) NH2-CH2-COOH + HCl -> (NH3-CH2-COOH)Cl
2) (NH3-CH2-COOH)Cl + NaOH -> NH2-CH2-COOH + NaCL+H2O
3) NH2-CH2-COOH+HCl->(NH3-CH2-COOH)Cl