for these three questions, please explain how can I solve them. thank you

The heat of combustion of H2,C and CH4 are: 285.8kJ/moleH2,393.5kJ/moleC and 890.4kJ/ mole CH4, respectively. Calculate H for the reaction: C(s)+2H2(g)CH4(g) Hint: Write the combustion reactions for H2,C and CH4 Calculate H for the reaction NO(g)+O(g)NO2(g) Given the following information: 1. NO(g)+O3(g)NO2(g)+O2(g)H=198.9kJ 2. 03(g)2302(g)H=142.3kJ 3. 02(g)20(g)H=495.0kJ Calculate H for the reaction 2C(s)+H2(g)C2H2(g) Given the following chemical equations and their respective enthalpy changes: 1. C2H2(g)+25O2(g)2CO2(g)+H2O(l)H=1299.6kJ 2. C(s)+O2(g)CO2(g)H=393.5kJ 3. H2(g)+21O2(g)H2O(l)H=285.8kJ