Salts are formed by metals, oxides or hydroxides from the cation side, and oxides or acids (sometimes nonmetals) from the anion side. Hence you can start from
4Ca + 10HNO3 = 4Ca(NO3)2 + NH4NO3 + 3H2O
CaO + 2HNO3 = Ca(NO3)2 + H2O
Ca(OH)2 + 2HNO3 = Ca(NO3)2 + 2H2O
Calcium hydroxide dissociates completely in water solution. This cause that CaOH+ is something exotic formula, but "parent base" also..